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A007801 | Expansion of f(f(x)), where f = x + x^2 + x^4 + x^8 + x^16 + ... | [
"1",
"2",
"2",
"3",
"6",
"8",
"8",
"16",
"22",
"40",
"80",
"146",
"240",
"356",
"488",
"661",
"870",
"1184",
"1936",
"3750",
"7976",
"17628",
"37528",
"74828",
"140480",
"249444",
"420392",
"678432",
"1056600",
"1593512",
"2334928",
"3337410",
"4660246",
"6364080",
"8527984",
"11258182",
"14753032",
"19622940",
"27836440"
] | [
"nonn"
] | 28 | 1 | 2 | null | null | Jeffrey Shallit | 2020-03-20T19:15:18 | oeisdata/seq/A007/A007801.seq | ccbd7157dde240dbaeb5574542932ebc |
A007802 | Numbers n such that game of n X n Button Madness need have no solution; this lists only the primitive elements of the set. | [
"3",
"5",
"17",
"31",
"127",
"257",
"511",
"683",
"2047",
"2731",
"3277",
"3641",
"8191",
"43691",
"52429",
"61681",
"65537",
"85489",
"131071",
"174763",
"178481",
"233017",
"253241",
"256999",
"486737",
"524287",
"704093",
"838861",
"1016801",
"1082401",
"1657009",
"1838599",
"1965379",
"2304167",
"2796203",
"3033169",
"3303821"
] | [
"nonn"
] | 37 | 1 | 1 | [
"A000668",
"A007802",
"A019434",
"A165740"
] | null | Aart Blokhuis (aartb(AT)win.tue.nl), Mar 15 1996 | 2015-04-22T16:04:57 | oeisdata/seq/A007/A007802.seq | 9231f6550d75705371256f0fe3e4b193 |
A007803 | Number of connected series-parallel graphs with a longest path of at most n edges and also a largest cut set of at most n edges. | [
"1",
"7",
"87",
"3503",
"425803",
"154793519"
] | [
"nonn",
"more"
] | 7 | 1 | 2 | null | null | michelb(AT)watson.ibm.com (Michel Berkelaar) | 2023-10-11T23:14:51 | oeisdata/seq/A007/A007803.seq | 381e54c9c2a6d981033e0be403ffb8a7 |
A007804 | Related to the asymptotic expansion of Sum_{k = 0..n} C(n,k)^4. | [
"1",
"30",
"1730",
"152340",
"18177750",
"2742927876",
"500848449300",
"107365679361000",
"26431620161451750",
"7348772237141884500",
"2277376143931016207100",
"778374526612873263759000",
"290867891728117751744917500"
] | [
"nonn"
] | 13 | 0 | 2 | [
"A005260",
"A007804"
] | null | Bruno Haible | 2013-10-07T01:26:32 | oeisdata/seq/A007/A007804.seq | 11a3c6f5c14270f1a6d3349f18fc8d8d |
A007805 | a(n) = Fibonacci(6*n + 3)/2. | [
"1",
"17",
"305",
"5473",
"98209",
"1762289",
"31622993",
"567451585",
"10182505537",
"182717648081",
"3278735159921",
"58834515230497",
"1055742538989025",
"18944531186571953",
"339945818819306129",
"6100080207560938369"
] | [
"nonn",
"nice",
"easy"
] | 116 | 0 | 2 | [
"A000045",
"A007805",
"A094954",
"A188647",
"A238379"
] | null | James A. Raymond, Clark Kimberling | 2023-02-25T03:07:51 | oeisdata/seq/A007/A007805.seq | 83d7b05f502c986b6230ace5b8bfbaf6 |
A007806 | Integer part of Sum_{i=1..n} binomial(n,i) * (n/i)^i. | [
"1",
"5",
"16",
"50",
"147",
"422",
"1210",
"3459",
"9878",
"28189",
"80425",
"229411",
"654311",
"1866003",
"5321194",
"15173321",
"43264523",
"123357771",
"351712022",
"1002758190",
"2858875748",
"8150529454",
"23236408366",
"66243882238",
"188849982251",
"538372895393",
"1534776215805",
"4375251800924"
] | [
"nonn"
] | 19 | 1 | 2 | null | null | Joseph Lavinus Ganley [ ganley(AT)virginia.edu ] | 2020-03-06T09:52:32 | oeisdata/seq/A007/A007806.seq | 5380c83d9b240cbc8516e0570ac4f53d |
A007807 | A variation on Euclid: a(n)=g(n)-1, where g(0)=0, g(1)=1, g(n+1)=g(n)(g(n-1)+1). | [
"0",
"0",
"1",
"3",
"11",
"59",
"779",
"47579",
"37159979",
"1768109008379",
"65702897157329640779",
"116169884340604934905464739377179",
"7632697963609645128663145969343357330533515068777579"
] | [
"nonn"
] | 12 | 1 | 4 | [
"A005831",
"A007807"
] | null | mays(AT)math.wvu.edu (Mike Mays) | 2025-01-05T19:51:34 | oeisdata/seq/A007/A007807.seq | ab7c6f8ddf2ba201cc5f6a6e75be376f |
A007808 | Number of directed column-convex polyominoes of height n: a(k+1)=(k+1)*a(k)+(a(1)+...+a(k)). | [
"1",
"1",
"3",
"13",
"69",
"431",
"3103",
"25341",
"231689",
"2345851",
"26065011",
"315386633",
"4128697741",
"58145826519",
"876660153671",
"14089181041141",
"240455356435473",
"4343224875615731",
"82776756452911579",
"1660133837750060001",
"34950186057896000021",
"770651602576606800463"
] | [
"nonn"
] | 65 | 0 | 3 | [
"A007808",
"A056542"
] | null | Paul Zimmermann | 2024-08-03T07:10:15 | oeisdata/seq/A007/A007808.seq | 47f259ca3266a7dbbb1b66c18b4241e2 |
A007809 | Smallest prime with n distinct digits. | [
"2",
"13",
"103",
"1039",
"10243",
"102359",
"1023467",
"10234589",
"102345689"
] | [
"nonn",
"fini",
"base",
"full"
] | 23 | 1 | 1 | [
"A007809",
"A007810",
"A038378",
"A071360",
"A071361",
"A071362",
"A071363"
] | null | N.B. Backhouse (sx52(AT)liverpool.ac.uk) | 2021-02-13T14:00:30 | oeisdata/seq/A007/A007809.seq | 4a0d7a858bd7b5e0b3b943389a55a92a |
A007810 | Largest prime with n distinct decimal digits. | [
"7",
"97",
"983",
"9871",
"98731",
"987631",
"9876413",
"98765431",
"987654103"
] | [
"nonn",
"fini",
"base",
"full"
] | 14 | 1 | 1 | [
"A007810",
"A071360",
"A071361",
"A071362",
"A071363"
] | null | N. B. Backhouse (sx52(AT)liverpool.ac.uk) | 2019-09-16T17:11:06 | oeisdata/seq/A007/A007810.seq | 597a86bac6d5b68ee37e76fd35c0fc31 |
A007811 | Numbers k for which 10k+1, 10k+3, 10k+7 and 10k+9 are primes. | [
"1",
"10",
"19",
"82",
"148",
"187",
"208",
"325",
"346",
"565",
"943",
"1300",
"1564",
"1573",
"1606",
"1804",
"1891",
"1942",
"2101",
"2227",
"2530",
"3172",
"3484",
"4378",
"5134",
"5533",
"6298",
"6721",
"6949",
"7222",
"7726",
"7969",
"8104",
"8272",
"8881",
"9784",
"9913",
"10111",
"10984",
"11653",
"11929",
"12220",
"13546",
"14416",
"15727"
] | [
"nonn"
] | 65 | 1 | 2 | [
"A007530",
"A007811",
"A008471",
"A010051",
"A014561",
"A024912",
"A032352",
"A102338",
"A102342",
"A102700",
"A125855",
"A216292",
"A216293",
"A245304",
"A245305"
] | null | N. J. A. Sloane and J. H. Conway, Mar 15 1996 | 2024-07-07T21:05:29 | oeisdata/seq/A007/A007811.seq | ab2313794403a69885b6b4edbb79d64b |
A007812 | Number of n-node Steinhaus graphs whose complements have at least one cut-vertex. | [
"0",
"1",
"3",
"2",
"6",
"17",
"33",
"56",
"72",
"88",
"114",
"140",
"160",
"190",
"211",
"250",
"290",
"322",
"356",
"404",
"438",
"474",
"530",
"580",
"626",
"682",
"728"
] | [
"nonn",
"more"
] | 14 | 1 | 3 | null | null | Wayne M. Dymacek (dymacek(AT)fs.sciences.wlu.edu) | 2020-04-25T03:54:40 | oeisdata/seq/A007/A007812.seq | 4f9930e1d3090b3cecdfec2de630a4e2 |
A007813 | Number of planar Steinhaus graphs with n nodes. | [
"1",
"2",
"4",
"8",
"16",
"32",
"59",
"75",
"65",
"56",
"50",
"44",
"36",
"31",
"27",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26",
"26"
] | [
"nonn"
] | 6 | 1 | 2 | null | null | Wayne M. Dymacek (wdymacek(AT)wlu.edu) | 2004-06-12T03:00:00 | oeisdata/seq/A007/A007813.seq | 9992d7747555080c34f8d44285e0de45 |
A007814 | Exponent of highest power of 2 dividing n, a.k.a. the binary carry sequence, the ruler sequence, or the 2-adic valuation of n. | [
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"4",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"5",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"4",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"6",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"4",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"5",
"0",
"1",
"0",
"2",
"0",
"1",
"0",
"3",
"0",
"1",
"0",
"2",
"0",
"1",
"0"
] | [
"nonn",
"nice",
"easy"
] | 502 | 1 | 4 | [
"A000079",
"A002487",
"A006519",
"A007814",
"A007949",
"A011371",
"A050602",
"A050603",
"A050605",
"A051064",
"A053398",
"A055457",
"A063787",
"A086463",
"A088705",
"A094267",
"A112765",
"A122840",
"A122841",
"A135416",
"A136480",
"A214411",
"A215366",
"A220466",
"A281264",
"A285406",
"A346070"
] | null | John Tromp, Dec 11 1996 | 2025-02-16T08:32:31 | oeisdata/seq/A007/A007814.seq | a84881646e0dc8d8305e4dcfe3d21027 |
A007815 | Number of triangulations of cyclic 3-polytope C(3,n+3). | [
"1",
"2",
"6",
"25",
"138",
"972",
"8477",
"89405",
"1119280",
"16384508",
"276961252",
"5349351298",
"116985744912",
"2873993336097",
"78768494976617",
"2393723937214795",
"80219694787925916",
"2950178878348113995",
"118538338070529618803"
] | [
"hard",
"nonn",
"changed"
] | 30 | 1 | 2 | [
"A007815",
"A028441"
] | null | reiner(AT)math.umn.edu (Victor Reiner), edelman(AT)math.umn.edu (Paul Edelman) | 2025-04-22T12:38:39 | oeisdata/seq/A007/A007815.seq | ce6bbcd10073908f434779e67866587a |
A007816 | Number of abstract simplicial 2-complexes on {1,2,3,...,n+3} which triangulate the 2-sphere: C(n+3,2)*(4n+1)!/(3n+3)!. | [
"1",
"10",
"195",
"5712",
"223440",
"10929600",
"641277000",
"43859692800",
"3424685806080",
"300495408595200",
"29262949937020800",
"3131187613956864000",
"365112996737448960000",
"46075561988281233408000"
] | [
"nonn",
"easy",
"nice"
] | 32 | 1 | 2 | null | null | Victor Reiner (reiner(AT)math.umn.edu), Paul Edelman (edelman(AT)math.umn.edu) | 2022-11-17T09:19:34 | oeisdata/seq/A007/A007816.seq | 2cd5eeaaa4da59c84ac6590145f3c34a |
A007817 | Number of abstract simplicial 2-complexes on {1,2,3,...,n+4} which triangulate a Moebius band in such a way that all vertices lie on the boundary and are traversed in the order 1,2,3,... as one goes around the boundary. | [
"1",
"14",
"113",
"720",
"4033",
"20864",
"102356",
"483680",
"2223482",
"10009570",
"44330931",
"193798624",
"838329841",
"3595080184",
"15305823256",
"64766503744",
"272635026526",
"1142528179324",
"4769415499234",
"19842220567264",
"82303947852506",
"340491603805344",
"1405318295426488",
"5788074933453632",
"23794580648906708",
"97653338015578634",
"400157876088981431"
] | [
"nonn",
"easy",
"nice"
] | 36 | 5 | 2 | null | null | Victor Reiner (reiner(AT)math.umn.edu), Paul Edelman (edelman(AT)math.umn.edu) | 2022-09-08T08:44:35 | oeisdata/seq/A007/A007817.seq | 8adc3a17d6f127640ff59aa19ee3734b |
A007818 | Maximal number of bonds joining n nodes in simple cubic lattice. | [
"0",
"1",
"2",
"4",
"5",
"7",
"9",
"12",
"13",
"15",
"17",
"20",
"21",
"23",
"25",
"28",
"30",
"33",
"34",
"36",
"38",
"41",
"43",
"46",
"48",
"51",
"54",
"55",
"57",
"59",
"62",
"64",
"67",
"69",
"72",
"75",
"76",
"78",
"80",
"83",
"85",
"88",
"90",
"93",
"96",
"98",
"101",
"104",
"105",
"107",
"109",
"112",
"114",
"117",
"119",
"122",
"125",
"127",
"130",
"133",
"135",
"138",
"141"
] | [
"nonn"
] | 25 | 1 | 3 | [
"A007818",
"A193416"
] | null | D. Heuer (heuer(AT)isnd23.in2p3.fr) | 2021-08-22T19:15:10 | oeisdata/seq/A007/A007818.seq | 5f9df4dfbb9290ae1467d5b788f04e64 |
A007819 | a(n) = Sum_{j=1..n} binomial(n^2, j). | [
"1",
"10",
"129",
"2516",
"68405",
"2391495",
"102022809",
"5130659560",
"296881218693",
"19415908147835",
"1415538531617771",
"113796709835547766",
"9998149029974754103",
"952980844872975079231",
"97930011125976327934825"
] | [
"nonn",
"easy"
] | 15 | 1 | 2 | [
"A007819",
"A066382"
] | null | Joseph Lavinus Ganley (jwl8k(AT)server.cs.Virginia.EDU) | 2022-09-08T08:44:35 | oeisdata/seq/A007/A007819.seq | e7ad50b9ed2e32ab555649c657b7b84c |
A007820 | Stirling numbers of second kind S(2n,n). | [
"1",
"1",
"7",
"90",
"1701",
"42525",
"1323652",
"49329280",
"2141764053",
"106175395755",
"5917584964655",
"366282500870286",
"24930204590758260",
"1850568574253550060",
"148782988064375309400",
"12879868072770626040000",
"1194461517469807833782085",
"118144018577011378596484455"
] | [
"nonn",
"easy",
"changed"
] | 72 | 0 | 3 | [
"A002465",
"A007820",
"A008277",
"A187646",
"A191236",
"A217913",
"A217914",
"A217915",
"A247238"
] | null | kemp(AT)sads.informatik.uni-frankfurt.de (Rainer Kemp) | 2025-04-15T05:09:47 | oeisdata/seq/A007/A007820.seq | aa01620c1dfb19b98961816d5e798884 |
A007821 | Primes p such that pi(p) is not prime. | [
"2",
"7",
"13",
"19",
"23",
"29",
"37",
"43",
"47",
"53",
"61",
"71",
"73",
"79",
"89",
"97",
"101",
"103",
"107",
"113",
"131",
"137",
"139",
"149",
"151",
"163",
"167",
"173",
"181",
"193",
"197",
"199",
"223",
"227",
"229",
"233",
"239",
"251",
"257",
"263",
"269",
"271",
"281",
"293",
"307",
"311",
"313",
"317",
"337",
"347",
"349",
"359",
"373"
] | [
"nonn"
] | 73 | 1 | 1 | [
"A000040",
"A006450",
"A007821",
"A018252",
"A038580",
"A049076",
"A049078",
"A049079",
"A049080",
"A049081",
"A058322",
"A058324",
"A058325",
"A058326",
"A058327",
"A058328",
"A078782",
"A093046",
"A102615",
"A102616",
"A102617",
"A270792",
"A270794",
"A270795",
"A270796"
] | null | Monte J. Zerger (mzerger(AT)cc4.adams.edu), Clark Kimberling | 2024-10-20T03:54:11 | oeisdata/seq/A007/A007821.seq | fe27ccd5200d1940e2517b37350df123 |
A007822 | Number of symmetric foldings of 2n+1 stamps. | [
"1",
"1",
"3",
"9",
"28",
"89",
"287",
"935",
"3072",
"10157",
"33767",
"112736",
"377836",
"1270203",
"4282311",
"14470629",
"49005732",
"166261653",
"565055147",
"1923186472",
"6554868916",
"22367933148",
"76417819396",
"261335128098",
"894597454360",
"3064970675173"
] | [
"nonn"
] | 23 | 1 | 3 | [
"A001010",
"A007822"
] | null | Stéphane Legendre | 2014-01-13T09:35:55 | oeisdata/seq/A007/A007822.seq | 4b10df21b9af6ac1d2d5bc4c0bffd475 |
A007823 | A007824(n)/16. | [
"1",
"2",
"5",
"14",
"45",
"186",
"945",
"5778",
"44037",
"403470",
"4344877",
"56072378",
"793804721",
"12734185106",
"229632768005",
"4628786367502",
"105803768420397",
"2626282179198138",
"71539181027191729",
"2076395667668755090",
"65704452165048754181"
] | [
"nonn"
] | 11 | 0 | 2 | null | null | Ralph Buchholz [ ralph(AT)defcen.gov.au ], Leisa Condie | 2013-07-19T05:02:43 | oeisdata/seq/A007/A007823.seq | f489245290ab32ccfb05d8c5e2531bfe |
A007824 | a(n) = f(a(n-1)), with f(m) = Sum i*b(i)*2^(i-1), m = Sum b(i)*2^i, and starting value 16. | [
"16",
"32",
"80",
"224",
"720",
"2976",
"15120",
"92448",
"704592",
"6455520",
"69518032",
"897158048",
"12700875536",
"203746961696",
"3674124288080",
"74060581880032",
"1692860294726352",
"42020514867170208",
"1144626896435067664",
"33222330682700081440"
] | [
"nonn"
] | 17 | 0 | 1 | [
"A007823",
"A007824",
"A136013"
] | null | Ralph Buchholz [ ralph(AT)defcen.gov.au ], Leisa Condie | 2020-09-06T11:12:28 | oeisdata/seq/A007/A007824.seq | 824758e070e1cc6cfac8f3efb567d3ca |
A007825 | Number of n step self-avoiding walks on 3 X infinity grid starting from (0,1). | [
"1",
"4",
"10",
"22",
"42",
"90",
"182",
"382",
"742",
"1486",
"2866",
"5646",
"10878",
"21198",
"40694",
"78758",
"151018",
"291046",
"557746",
"1072050",
"2053586",
"3941038",
"7547726",
"14471102",
"27711106",
"53099670",
"101675030",
"194762778",
"372916642",
"714195242"
] | [
"nonn",
"walk"
] | 19 | 0 | 2 | [
"A001411",
"A007825",
"A038577",
"A302408"
] | null | Lauren Williams (lwilliam(AT)MIT.EDU) | 2018-04-15T21:48:45 | oeisdata/seq/A007/A007825.seq | d728153cb0c206fd8eb6aca2cc7257ed |
A007826 | Numbered stops on the Market-Frankford rapid transit (SEPTA) railway line in Philadelphia, PA USA. | [
"2",
"5",
"8",
"11",
"13",
"15",
"30",
"34",
"40",
"46",
"52",
"56",
"60",
"63",
"69"
] | [
"nonn",
"fini",
"full"
] | 29 | 1 | 1 | [
"A000053",
"A000054",
"A001049",
"A007826"
] | null | N. J. A. Sloane | 2018-11-27T08:22:02 | oeisdata/seq/A007/A007826.seq | c7a9c1db65bc676d728dbf435fbf7b75 |
A007827 | Number of homeomorphically irreducible (or series-reduced) trees with n pendant nodes, or continua with n non-cut points, or leaves. | [
"1",
"1",
"1",
"1",
"2",
"3",
"7",
"13",
"32",
"73",
"190",
"488",
"1350",
"3741",
"10765",
"31311",
"92949",
"278840",
"847511",
"2599071",
"8044399",
"25082609",
"78758786",
"248803504",
"790411028",
"2523668997",
"8095146289",
"26076714609",
"84329102797",
"273694746208"
] | [
"nonn",
"nice",
"easy"
] | 38 | 0 | 5 | [
"A000014",
"A000055",
"A000311",
"A000669",
"A007827",
"A059123",
"A064060",
"A271205"
] | null | Matthew Cropper (mmcrop01(AT)athena.louisville.edu). | 2023-11-20T09:27:51 | oeisdata/seq/A007/A007827.seq | 1045afae8d1399818d60df009cd577e8 |
A007828 | Largest t such that a spherical t-design with n points exists in 3 dimensions. | [
"0",
"1",
"1",
"2",
"1",
"3",
"2",
"3",
"2",
"3",
"3",
"5",
"3",
"4",
"3",
"5",
"4",
"5",
"4",
"5",
"4",
"5",
"5",
"7",
"5",
"6",
"5",
"6",
"6",
"7",
"6",
"7",
"6",
"7",
"6",
"8",
"7",
"7",
"7",
"8",
"7",
"8",
"7",
"8",
"8",
"8",
"8",
"9",
"8",
"9",
"8",
"9",
"8",
"9",
"9",
"9",
"9",
"9",
"9",
"10",
"9",
"9",
"9",
"10"
] | [
"nonn",
"nice"
] | 12 | 1 | 4 | [
"A007828",
"A076868",
"A076870"
] | null | N. J. A. Sloane, R. H. Hardin | 2018-07-08T19:55:47 | oeisdata/seq/A007/A007828.seq | 0fb7fffd5551baa711c731a6e886f645 |
A007829 | From random walks on complete directed triangle. | [
"0",
"0",
"0",
"0",
"0",
"6",
"8",
"28",
"44",
"100",
"162",
"318",
"514",
"942",
"1518",
"2672",
"4302",
"7380",
"11882",
"20040",
"32276",
"53810",
"86710",
"143396",
"231204",
"380152",
"613286",
"1004188",
"1620864",
"2645928",
"4272744",
"6959326",
"11242518",
"18281222",
"29542078",
"47978666",
"77552928",
"125836374",
"203445784"
] | [
"nonn",
"walk"
] | 19 | 0 | 6 | [
"A000931",
"A007829",
"A084338"
] | null | Eric Bussian [ ebussian(AT)math.gatech.edu ] | 2020-03-11T17:18:22 | oeisdata/seq/A007/A007829.seq | bbe54c098098e56b875abe232bbf8b3b |
A007830 | a(n) = (n+3)^n. | [
"1",
"4",
"25",
"216",
"2401",
"32768",
"531441",
"10000000",
"214358881",
"5159780352",
"137858491849",
"4049565169664",
"129746337890625",
"4503599627370496",
"168377826559400929",
"6746640616477458432",
"288441413567621167681",
"13107200000000000000000",
"630880792396715529789561"
] | [
"nonn",
"nice",
"easy"
] | 78 | 0 | 2 | [
"A000169",
"A000272",
"A000312",
"A007778",
"A007830",
"A008785",
"A008786",
"A008787",
"A008788",
"A008789",
"A008790",
"A008791"
] | null | Peter J. Cameron, Mar 15 1996 | 2023-01-20T17:43:58 | oeisdata/seq/A007/A007830.seq | eea7c0d827eeff8e74ed2a0866f9dbff |
A007831 | Number of edge-labeled series-reduced trees with n nodes. | [
"1",
"0",
"1",
"1",
"16",
"61",
"806",
"6329",
"89272",
"1082281",
"17596162",
"284074165",
"5407229972",
"107539072733",
"2380274168806",
"55833426732529",
"1418006883852784",
"38195636967960913",
"1097755724834189834",
"33345176998235584301",
"1071124330593423824908",
"36203857373308709200645"
] | [
"nonn"
] | 21 | 1 | 5 | [
"A005512",
"A007831"
] | null | Peter J. Cameron | 2022-09-08T08:44:35 | oeisdata/seq/A007/A007831.seq | efdf2e5e6694e32a3167f46475b90c5d |
A007832 | Number of point labeled 5,6-free two-graphs with n nodes. | [
"1",
"1",
"2",
"8",
"52",
"457",
"4979",
"64591",
"972906",
"16701834",
"322063458",
"6894918021",
"162316253829",
"4168330738093",
"115980086558470",
"3476156853885992",
"111665862911781864",
"3827642575341002133",
"139457935266705019299",
"5382149182666970080019",
"219344947692643001216702"
] | [
"nonn"
] | 17 | 1 | 3 | [
"A007831",
"A007832"
] | null | Peter J. Cameron | 2024-10-15T18:07:08 | oeisdata/seq/A007/A007832.seq | 8d8570281de61f403ff6c5168849f36e |
A007833 | Number of point-labeled reduced two-graphs with n nodes. | [
"1",
"0",
"1",
"1",
"28",
"448",
"18788",
"1419852",
"207249896",
"58206408344",
"31725488477648",
"33830818147141904",
"71068681534173472576",
"295648155633330113713344",
"2444510010072634827916776064",
"40269686339597630128483872278656",
"1323732128140903183968664175047409152"
] | [
"nonn"
] | 17 | 1 | 5 | [
"A007833",
"A092430"
] | null | Peter J. Cameron | 2019-04-29T16:36:57 | oeisdata/seq/A007/A007833.seq | a22568376713693cbc0d52cfa305ab8e |
A007834 | Number of point labeled reduced 5-free two-graphs with n nodes. | [
"1",
"0",
"1",
"1",
"16",
"76",
"1016",
"10284",
"157340",
"2411756",
"44953712",
"899824256",
"20283419872",
"495216726096",
"13202082981712",
"378896535199888",
"11690436112988224",
"385173160930360192",
"13509981115738946816",
"502374681770910293568",
"19746124320077115154112",
"817908018939079281840320"
] | [
"nonn"
] | 18 | 1 | 5 | [
"A007831",
"A007832",
"A007833",
"A007834",
"A359986",
"A361355"
] | null | Peter J. Cameron | 2024-10-15T18:07:03 | oeisdata/seq/A007/A007834.seq | 178e19bf7577768e5d13a1920d708d9a |
A007835 | Number of unordered sets of pairs (in-degree, out-degree) for nodes of directed trees on n unlabeled nodes (the edges are directed in arbitrary directions, the tree is unrooted). | [
"1",
"1",
"3",
"8",
"21",
"52",
"124",
"284",
"629",
"1352",
"2829",
"5777",
"11544"
] | [
"nonn",
"more"
] | 22 | 1 | 3 | [
"A000238",
"A007835"
] | null | Philippe Aubry (philippe.aubry(AT)oncfs.gouv.fr), Oct 02 1994 | 2018-02-05T03:20:24 | oeisdata/seq/A007/A007835.seq | 012898fb0718570b439fa1fcd9ac5426 |
A007836 | Springer numbers associated with symplectic group. | [
"1",
"1",
"1",
"5",
"23",
"151",
"1141",
"10205",
"103823",
"1190191",
"15151981",
"212222405",
"3242472023",
"53670028231",
"956685677221",
"18271360434605",
"372221031054623",
"8056751598834271",
"184647141575344861",
"4466900836910758805"
] | [
"nonn",
"nice"
] | 49 | 0 | 4 | [
"A001586",
"A007836",
"A104035",
"A155100",
"A156142"
] | null | N. J. A. Sloane | 2021-12-17T05:28:29 | oeisdata/seq/A007/A007836.seq | 31ce7d9bef82c446995abe2fe6392782 |
A007837 | Number of partitions of n-set with distinct block sizes. | [
"1",
"1",
"1",
"4",
"5",
"16",
"82",
"169",
"541",
"2272",
"17966",
"44419",
"201830",
"802751",
"4897453",
"52275409",
"166257661",
"840363296",
"4321172134",
"24358246735",
"183351656650",
"2762567051857",
"10112898715063",
"62269802986835",
"343651382271526",
"2352104168848091",
"15649414071734847"
] | [
"nonn"
] | 80 | 0 | 4 | [
"A000110",
"A005651",
"A007837",
"A007838",
"A032011",
"A035470",
"A038041",
"A131632",
"A178682",
"A262072",
"A262078",
"A265950",
"A271423",
"A275780",
"A309992",
"A326026",
"A326514",
"A326517",
"A326533",
"A327869"
] | null | Arnold Knopfmacher | 2022-03-18T13:05:52 | oeisdata/seq/A007/A007837.seq | 029a67a770eb4acdef14550b03a364de |
A007838 | Number of permutations of n elements with distinct cycle lengths. | [
"1",
"1",
"1",
"5",
"14",
"74",
"474",
"3114",
"24240",
"219456",
"2231280",
"23753520",
"288099360",
"3692907360",
"51677246880",
"775999798560",
"12364465397760",
"208583679951360",
"3770392002048000",
"71251563061002240",
"1421847102467635200",
"29861872557056870400",
"655829140087057305600"
] | [
"nonn"
] | 70 | 0 | 4 | [
"A000142",
"A007838",
"A080130",
"A087639",
"A088994",
"A317166"
] | null | Arnold Knopfmacher | 2022-02-24T20:25:49 | oeisdata/seq/A007/A007838.seq | 8ffbcb77bc6b2620207b46f6322f449c |
A007839 | Number of polynomials of degree n over GF(2) in which the degrees of all irreducible factors are distinct. | [
"1",
"2",
"1",
"4",
"7",
"14",
"28",
"54",
"111",
"218",
"436",
"854",
"1735",
"3432",
"6825",
"13664",
"27352",
"54218",
"108714",
"216616",
"432239",
"864548",
"1727408",
"3441364",
"6891458",
"13756440",
"27466896",
"54922134",
"109751871",
"219035562",
"438319568",
"875529382"
] | [
"nonn",
"easy",
"nice"
] | 31 | 0 | 2 | null | null | Arnold Knopfmacher | 2017-02-08T12:52:38 | oeisdata/seq/A007/A007839.seq | 1021468c25a3a40f4789b65b2ccf3588 |
A007840 | Number of factorizations of permutations of n letters into ordered cycles. | [
"1",
"1",
"3",
"14",
"88",
"694",
"6578",
"72792",
"920904",
"13109088",
"207360912",
"3608233056",
"68495486640",
"1408631978064",
"31197601660080",
"740303842925184",
"18738231641600256",
"503937595069600896",
"14349899305396086912",
"431322634732516137216",
"13646841876634025159424"
] | [
"nonn"
] | 92 | 0 | 3 | [
"A007840",
"A039814",
"A052860",
"A111492",
"A238385"
] | null | Arnold Knopfmacher | 2021-04-17T03:40:21 | oeisdata/seq/A007/A007840.seq | 2d356e047105d91d911c57ba06b86ba8 |
A007841 | Number of factorizations of permutations of n letters into cycles in nondecreasing length order. | [
"1",
"1",
"3",
"11",
"56",
"324",
"2324",
"18332",
"167544",
"1674264",
"18615432",
"223686792",
"2937715296",
"41233157952",
"623159583552",
"10008728738304",
"171213653641344",
"3092653420877952",
"59086024678203264",
"1185657912197967744",
"25015435198774723584",
"552130504313534175744"
] | [
"nonn"
] | 48 | 0 | 3 | [
"A007837",
"A007838",
"A007841",
"A249078",
"A249480",
"A249588",
"A249593",
"A269791",
"A269793",
"A269794"
] | null | Arnold Knopfmacher | 2019-07-24T08:09:21 | oeisdata/seq/A007/A007841.seq | 5abdf0626417d6c4b01d33e7212cae52 |
A007842 | Largest determinant of 2n+1 X 2n+1 matrix with entries +-1 and 0 diagonal. | [
"2",
"22",
"394",
"8760",
"240786"
] | [
"nonn",
"hard",
"more"
] | 8 | 1 | 1 | null | null | N. J. A. Sloane. | 2012-03-30T16:45:17 | oeisdata/seq/A007/A007842.seq | a7d3b009700f30400cb66ec64ca4e754 |
A007843 | Least positive integer k for which 2^n divides k!. | [
"1",
"2",
"4",
"4",
"6",
"8",
"8",
"8",
"10",
"12",
"12",
"14",
"16",
"16",
"16",
"16",
"18",
"20",
"20",
"22",
"24",
"24",
"24",
"26",
"28",
"28",
"30",
"32",
"32",
"32",
"32",
"32",
"34",
"36",
"36",
"38",
"40",
"40",
"40",
"42",
"44",
"44",
"46",
"48",
"48",
"48",
"48",
"50",
"52",
"52",
"54",
"56",
"56",
"56",
"58",
"60",
"60",
"62",
"64",
"64",
"64",
"64",
"64",
"64",
"66",
"68",
"68",
"70",
"72",
"72",
"72",
"74",
"76",
"76",
"78"
] | [
"nonn",
"easy",
"nice"
] | 83 | 0 | 2 | [
"A007814",
"A007843",
"A007844",
"A007845",
"A020646",
"A048841",
"A048846"
] | null | Bruce Dearden and Jerry Metzger; R. Muller | 2022-08-06T07:18:32 | oeisdata/seq/A007/A007843.seq | 748e5cf48ec0d8f697584e18986a1b68 |
A007844 | Least positive integer k for which 3^n divides k!. | [
"1",
"3",
"6",
"9",
"9",
"12",
"15",
"18",
"18",
"21",
"24",
"27",
"27",
"27",
"30",
"33",
"36",
"36",
"39",
"42",
"45",
"45",
"48",
"51",
"54",
"54",
"54",
"57",
"60",
"63",
"63",
"66",
"69",
"72",
"72",
"75",
"78",
"81",
"81",
"81",
"81",
"84",
"87",
"90",
"90",
"93",
"96",
"99",
"99",
"102",
"105",
"108",
"108",
"108",
"111",
"114",
"117",
"117",
"120",
"123",
"126",
"126",
"129",
"132",
"135",
"135",
"135"
] | [
"nonn"
] | 27 | 0 | 2 | [
"A007843",
"A007844",
"A007845",
"A120503"
] | null | Bruce Dearden and Jerry Metzger, R. Muller | 2019-12-30T12:22:02 | oeisdata/seq/A007/A007844.seq | e3bb900a3ddb004d652579300acfc1de |
A007845 | Least positive integer k for which 5^n divides k!. | [
"1",
"5",
"10",
"15",
"20",
"25",
"25",
"30",
"35",
"40",
"45",
"50",
"50",
"55",
"60",
"65",
"70",
"75",
"75",
"80",
"85",
"90",
"95",
"100",
"100",
"105",
"110",
"115",
"120",
"125",
"125",
"125",
"130",
"135",
"140",
"145",
"150",
"150",
"155",
"160",
"165",
"170",
"175",
"175",
"180",
"185",
"190",
"195",
"200",
"200",
"205",
"210",
"215",
"220",
"225",
"225",
"230",
"235",
"240",
"245"
] | [
"nonn"
] | 32 | 0 | 2 | [
"A007843",
"A007844",
"A007845",
"A027868"
] | null | Bruce Dearden and Jerry Metzger | 2020-01-03T05:28:55 | oeisdata/seq/A007/A007845.seq | 7d17631ffe021f20fe5bdaab6cfee4fb |
A007846 | There are three equivalent descriptions: 1. Number of (horizontally or vertically) connected arrays of 1..n on rectangular grid (otherwise zero) with only one local maximum. 2. Number of n-polyominoes labeled 1...n such that each successive labeled cell is the neighbor of a previously labeled cell. 3. Number of connected n-step paths on a rectangular lattice, diagonal or repeated steps not allowed. | [
"1",
"1",
"4",
"24",
"176",
"1504",
"14560",
"156768",
"1852512",
"23783264",
"329070176",
"4874845920",
"76898357216",
"1285734871520",
"22695759641440",
"421508294003424",
"8211642378316768"
] | [
"nonn",
"nice"
] | 9 | 0 | 3 | [
"A000079",
"A007846",
"A087518",
"A087783"
] | null | Joel Yellin (yellin(AT)soe.ucsc.edu) | 2012-03-31T12:34:49 | oeisdata/seq/A007/A007846.seq | 82453d1d41a1bd0f44c15900a831b008 |
A007847 | Number of hyperplanes spanned by the vertices of an n-cube. | [
"2",
"6",
"20",
"140",
"3254",
"252434",
"71343208",
"86246755608",
"448691419804586"
] | [
"nonn",
"hard",
"more"
] | 32 | 1 | 1 | [
"A007847",
"A333539",
"A363505",
"A363506",
"A363512"
] | null | Oswin Aichholzer (oaich(AT)igi.tu-graz.ac.at) | 2023-06-09T09:54:06 | oeisdata/seq/A007/A007847.seq | db996faca66460bb4ad7beb190bed578 |
A007848 | Number of skew hyperplanes spanned by the vertices of an n-cube. | [
"2",
"2",
"8",
"88",
"2704",
"234688",
"69640192",
"85682904704"
] | [
"nonn",
"hard"
] | 6 | 1 | 1 | null | null | Oswin Aichholzer (oaich(AT)igi.tu-graz.ac.at) | 2015-04-05T02:07:39 | oeisdata/seq/A007/A007848.seq | 85ffb8fb27aa3927427c6cc3e9b2f007 |
A007849 | Number of hyperplanes spanned by the vertices of an n-cube that cover exactly n vertices. | [
"2",
"6",
"8",
"80",
"2112",
"123648",
"23963648",
"25806963456"
] | [
"nonn",
"hard",
"nice"
] | 6 | 1 | 1 | null | null | Oswin Aichholzer (oaich(AT)igi.tu-graz.ac.at) | 2015-04-05T02:10:57 | oeisdata/seq/A007/A007849.seq | 592dd8bc7af136f37a6c924023575505 |
A007850 | Giuga numbers: composite numbers n such that p divides n/p - 1 for every prime divisor p of n. | [
"30",
"858",
"1722",
"66198",
"2214408306",
"24423128562",
"432749205173838",
"14737133470010574",
"550843391309130318",
"244197000982499715087866346",
"554079914617070801288578559178",
"1910667181420507984555759916338506"
] | [
"nonn",
"nice",
"hard",
"more"
] | 170 | 1 | 1 | [
"A007850",
"A054377",
"A216823",
"A216824",
"A235137",
"A235138",
"A235140",
"A235363",
"A236434",
"A326690"
] | null | D. Borwein, J. M. Borwein, P. B. Borwein and R. Girgensohn | 2025-02-16T08:32:31 | oeisdata/seq/A007/A007850.seq | eec884fc036599d7c48d38f127b00501 |
A007851 | Number of elements w of the Weyl group D(n) such that the roots sent negative by w span an Abelian subalgebra of the Lie algebra. | [
"1",
"4",
"14",
"48",
"167",
"593",
"2144",
"7864",
"29171",
"109173",
"411501",
"1560089",
"5943199",
"22732739",
"87253604",
"335897864",
"1296447899",
"5015206349",
"19439895089",
"75487384829",
"293595204239",
"1143532045499",
"4459774977449",
"17413705988873"
] | [
"nonn",
"easy"
] | 13 | 1 | 2 | null | null | C. Kenneth Fan [ ckfan(AT)MIT.EDU ] | 2020-01-30T21:29:14 | oeisdata/seq/A007/A007851.seq | a6fbd3380693322e3e9a4ee40d148b98 |
A007852 | Antichains in rooted plane trees on n nodes. | [
"1",
"2",
"7",
"29",
"131",
"625",
"3099",
"15818",
"82595",
"439259",
"2371632",
"12967707",
"71669167",
"399751019",
"2247488837",
"12723799989",
"72474333715",
"415046380767",
"2388355096446",
"13803034008095",
"80082677184820",
"466263828731640",
"2723428895205210",
"15954063529603565",
"93711351580424391"
] | [
"nonn",
"changed"
] | 66 | 1 | 2 | [
"A007440",
"A007852",
"A153294"
] | null | Martin Klazar, Mar 15 1996 | 2025-04-16T03:06:12 | oeisdata/seq/A007/A007852.seq | 5d35fff7003036d039884cfa5b40fbae |
A007853 | Number of maximal antichains in rooted plane trees on n nodes. | [
"1",
"2",
"5",
"15",
"50",
"178",
"663",
"2553",
"10086",
"40669",
"166752",
"693331",
"2917088",
"12398545",
"53164201",
"229729439",
"999460624",
"4374546305",
"19250233408",
"85120272755",
"378021050306",
"1685406494673",
"7541226435054",
"33852474532769",
"152415463629568",
"688099122024944"
] | [
"nonn"
] | 39 | 1 | 2 | [
"A000081",
"A000108",
"A001003",
"A001006",
"A007853",
"A126120",
"A213705",
"A317713",
"A318046",
"A318048",
"A318049"
] | null | Martin Klazar | 2019-11-07T19:37:11 | oeisdata/seq/A007/A007853.seq | aab0a5b5eb3b1d2bcfeff8e788d0112d |
A007854 | Expansion of 1/(1 - 3*x*C(x)), where C(x) = (1 - sqrt(1 - 4*x))/(2*x) = g.f. for the Catalan numbers A000108. | [
"1",
"3",
"12",
"51",
"222",
"978",
"4338",
"19323",
"86310",
"386250",
"1730832",
"7763550",
"34847796",
"156503064",
"703149438",
"3160160811",
"14206181382",
"63874779714",
"287242041528",
"1291872728826",
"5810776384932",
"26138647551564",
"117587214581508"
] | [
"nonn",
"easy"
] | 73 | 0 | 2 | [
"A000108",
"A000984",
"A007854",
"A067347",
"A076035",
"A076036",
"A116395",
"A126694"
] | null | Martin Klazar | 2024-06-01T11:53:25 | oeisdata/seq/A007/A007854.seq | a09a133d41144f8783aec2b93baae201 |
A007855 | Infima closed sets in rooted plane trees on n nodes. | [
"1",
"3",
"13",
"63",
"326",
"1769",
"9964",
"57843",
"344203",
"2090470",
"12912988",
"80899801",
"512896540",
"3284651548",
"21217493460",
"138080484819",
"904454380446",
"5958186674879",
"39448465279220",
"262359379484522",
"1751912981641794",
"11741044418866476"
] | [
"nonn"
] | 19 | 1 | 2 | null | null | Martin Klazar | 2019-04-05T10:06:14 | oeisdata/seq/A007/A007855.seq | 9d29312c75cb9a5395029416111c9f24 |
A007856 | Subtrees in rooted plane trees on n nodes. | [
"1",
"3",
"12",
"52",
"236",
"1109",
"5366",
"26639",
"135300",
"701269",
"3700400",
"19834973",
"107784622",
"592705377",
"3292970302",
"18458954896",
"104276682820",
"593056996445",
"3392898090908",
"19512100041995",
"112729617387020",
"653965783541960",
"3807766434556940"
] | [
"nonn"
] | 29 | 1 | 2 | null | null | Martin Klazar | 2019-08-04T18:22:23 | oeisdata/seq/A007/A007856.seq | 20d04c121b6fccb0c813d053a0563045 |
A007857 | Number of independent sets in rooted plane trees on n nodes. | [
"1",
"2",
"8",
"37",
"184",
"959",
"5172",
"28641",
"162008",
"932503",
"5445934",
"32197334",
"192357788",
"1159603592",
"7045356104",
"43098733353",
"265240985112",
"1641100253735",
"10202295895890",
"63696629668980",
"399216722146770",
"2510833297584165"
] | [
"nonn"
] | 42 | 1 | 2 | [
"A000108",
"A001764",
"A007226",
"A007857",
"A130523"
] | null | Martin Klazar | 2020-08-06T10:14:21 | oeisdata/seq/A007/A007857.seq | 68eae5d3bc53cb6f23ea9e48dbc7d1ad |
A007858 | G.f. is 1 - 1/f(x), where f(x) = 1+x+3*x^2+9*x^3+32*x^4+... is 1/x times g.f. for A063020. | [
"1",
"2",
"4",
"13",
"44",
"164",
"636",
"2559",
"10556",
"44440",
"190112",
"824135",
"3612244",
"15981632",
"71277736",
"320121747",
"1446537564",
"6571858168",
"30000766128",
"137544893940",
"633051803120",
"2923867281660",
"13547594977500",
"62955434735505",
"293336372858724",
"1370149533359784",
"6414423856436816"
] | [
"nonn"
] | 47 | 1 | 2 | [
"A000108",
"A007858"
] | null | Martin Klazar, Mar 15 1996 | 2025-03-26T13:26:34 | oeisdata/seq/A007/A007858.seq | 638c91bb3ab0eb72d39d6416b2828423 |
A007859 | Number of matchings in rooted plane trees on n nodes. | [
"0",
"1",
"4",
"18",
"84",
"405",
"2002",
"10101",
"51844",
"269994",
"1423784",
"7590044",
"40846390",
"221650195",
"1211606190"
] | [
"nonn",
"more"
] | 15 | 1 | 3 | null | null | Martin Klazar | 2019-04-05T10:00:20 | oeisdata/seq/A007/A007859.seq | 12b43f7a8e2a1bb7b66fae8800974d78 |
A007860 | Maximal matchings in rooted plane trees on n nodes. | [
"1",
"1",
"4",
"12",
"44",
"175",
"718",
"3052",
"13308",
"59139",
"266974",
"1220879",
"5643562",
"26327769",
"123793450",
"586078393",
"2791408028",
"13365916545",
"64302770488",
"310672722803",
"1506737267266",
"7332920012492",
"35800278685252",
"175286440178448",
"860517328379634",
"4234766396436095"
] | [
"nonn"
] | 18 | 1 | 3 | null | null | Martin Klazar (klazar(AT)kam.mff.cuni.cz) | 2018-02-08T15:26:03 | oeisdata/seq/A007/A007860.seq | 81713da019a096d3d4c0682f30a6c41b |
A007861 | Mahonian statistics on S_n which split (a(n)=n!.a(n-1)^n). | [
"1",
"2",
"48",
"127401984",
"4027747178726102955105561756869669557370880"
] | [
"nonn",
"easy"
] | 5 | 1 | 2 | null | null | Jennifer Galovich [ JGALOVICH(AT)tiny.computing.csbsju.edu ] | 2003-05-16T03:00:00 | oeisdata/seq/A007/A007861.seq | ccb4ed77d1f3e7b1fa744e1997817ba2 |
A007862 | Number of triangular numbers that divide n. | [
"1",
"1",
"2",
"1",
"1",
"3",
"1",
"1",
"2",
"2",
"1",
"3",
"1",
"1",
"3",
"1",
"1",
"3",
"1",
"2",
"3",
"1",
"1",
"3",
"1",
"1",
"2",
"2",
"1",
"5",
"1",
"1",
"2",
"1",
"1",
"4",
"1",
"1",
"2",
"2",
"1",
"4",
"1",
"1",
"4",
"1",
"1",
"3",
"1",
"2",
"2",
"1",
"1",
"3",
"2",
"2",
"2",
"1",
"1",
"5",
"1",
"1",
"3",
"1",
"1",
"4",
"1",
"1",
"2",
"2",
"1",
"4",
"1",
"1",
"3",
"1",
"1",
"4",
"1",
"2",
"2",
"1",
"1",
"5",
"1",
"1",
"2",
"1",
"1",
"6",
"2",
"1",
"2",
"1",
"1",
"3",
"1",
"1",
"2",
"2",
"1",
"3",
"1",
"1",
"5"
] | [
"nonn"
] | 50 | 1 | 3 | [
"A000005",
"A000217",
"A007294",
"A007862",
"A010054",
"A027750",
"A046951",
"A049988",
"A130317",
"A239930",
"A325324",
"A325327",
"A325407"
] | null | Richard Stanley | 2025-02-16T08:32:31 | oeisdata/seq/A007/A007862.seq | d854fc82f1ec9682508729c8b6d2c47d |
A007863 | Number of hybrid binary trees with n internal nodes. | [
"1",
"2",
"7",
"31",
"154",
"820",
"4575",
"26398",
"156233",
"943174",
"5785416",
"35955297",
"225914342",
"1432705496",
"9158708775",
"58954911423",
"381806076426",
"2485972170888",
"16263884777805",
"106858957537838",
"704810376478024",
"4664987368511948",
"30974829705533240",
"206266525653071416"
] | [
"nonn"
] | 104 | 0 | 2 | [
"A007788",
"A007863",
"A011365",
"A245049"
] | null | Jean Pallo (pallo(AT)u-bourgogne.fr) | 2023-05-16T12:10:42 | oeisdata/seq/A007/A007863.seq | 51e8045c78f4d1634c53a9a29cb516d6 |
A007864 | Number of matrix bundles of codimension n (Euler transform of A001156). | [
"1",
"2",
"4",
"7",
"11",
"19",
"30",
"49",
"76",
"118",
"180",
"276",
"411",
"614",
"908",
"1336",
"1944",
"2824",
"4067",
"5839",
"8326",
"11829",
"16719",
"23557",
"33019",
"46142",
"64226",
"89117",
"123198",
"169841",
"233373",
"319817",
"436982",
"595554",
"809503",
"1097714",
"1484805",
"2003938",
"2698410"
] | [
"nonn"
] | 10 | 1 | 2 | null | null | Peter J. Cameron | 2013-05-13T11:08:00 | oeisdata/seq/A007/A007864.seq | aac17a5f05af4e28958031310a5a49d8 |
A007865 | Number of sum-free subsets of {1, ..., n}. | [
"1",
"2",
"3",
"6",
"9",
"16",
"24",
"42",
"61",
"108",
"151",
"253",
"369",
"607",
"847",
"1400",
"1954",
"3139",
"4398",
"6976",
"9583",
"15456",
"20982",
"32816",
"45417",
"70109",
"94499",
"148234",
"200768",
"308213",
"415543",
"634270",
"849877",
"1311244",
"1739022",
"2630061",
"3540355",
"5344961",
"7051789",
"10747207",
"14158720",
"21295570",
"28188520"
] | [
"nonn",
"nice"
] | 76 | 0 | 2 | [
"A007865",
"A050291",
"A085489",
"A093970",
"A093971",
"A103580",
"A151897",
"A211316",
"A211317",
"A308546",
"A326020",
"A326080",
"A326083"
] | null | Peter J. Cameron | 2025-02-16T08:32:31 | oeisdata/seq/A007/A007865.seq | f8add13b94f54b5446710db3b620075e |
A007866 | Number of `homogenized' N-free graphs with n nodes. | [
"1",
"2",
"4",
"14",
"44",
"164",
"614"
] | [
"nonn",
"more"
] | 15 | 1 | 2 | null | null | Peter J. Cameron | 2016-02-03T10:20:24 | oeisdata/seq/A007/A007866.seq | 3e94da5bf95b795b001562a713620e98 |
A007867 | Complementary pairs of `homogenized' N-free graphs with n nodes. | [
"1",
"1",
"2",
"7",
"22",
"82",
"307"
] | [
"nonn"
] | 11 | 1 | 3 | [
"A007867",
"A241156"
] | null | Peter J. Cameron | 2016-02-03T10:43:07 | oeisdata/seq/A007/A007867.seq | 75c86a0ba7ee53ef8605f7917d36eace |
A007868 | Number of inverse pairs of elements in symmetric group S_n, or pairs of total orders on n nodes (average of A000085 and A000142). | [
"1",
"1",
"2",
"5",
"17",
"73",
"398",
"2636",
"20542",
"182750",
"1819148",
"19976248",
"239570876",
"3113794652",
"43590340840",
"653842358768",
"10461418047368",
"177843819947656",
"3201187351520912",
"60822552609266720",
"1216451015967652048",
"25545471145831066448",
"562000364198246159456"
] | [
"nonn",
"nice"
] | 27 | 0 | 3 | null | null | Peter J. Cameron | 2019-04-08T03:41:27 | oeisdata/seq/A007/A007868.seq | d208ed269ec81a813c433db566a54627 |
A007869 | Number of complementary pairs of graphs on n nodes. Also number of unlabeled graphs with n nodes and an even number of edges. | [
"1",
"1",
"2",
"6",
"18",
"78",
"522",
"6178",
"137352",
"6002584",
"509498932",
"82545586656",
"25251015686776",
"14527077828617744",
"15713242984902154384",
"32000507852263779299344",
"122967932076766466347469888",
"893788862572805850273939095424",
"12318904626562502262191503745716384"
] | [
"nonn",
"nice"
] | 39 | 1 | 3 | [
"A000088",
"A000171",
"A007869",
"A054960"
] | null | Peter J. Cameron | 2021-03-02T06:01:26 | oeisdata/seq/A007/A007869.seq | f54e1bb20101b25cc2adbec771f56991 |
A007870 | Determinant of character table of symmetric group S_n. | [
"1",
"1",
"2",
"6",
"96",
"2880",
"9953280",
"100329062400",
"10651768002183168000",
"150283391703941024789299200000",
"9263795272057860957392207640004657152000000000",
"16027108137650009941734148595388542471170145479274004480000000000000"
] | [
"nonn"
] | 74 | 0 | 3 | [
"A000041",
"A000142",
"A006128",
"A006906",
"A007870",
"A063073",
"A066186",
"A066633",
"A086644",
"A302246",
"A302247",
"A325501",
"A325504",
"A325507",
"A325536"
] | null | Peter J. Cameron, Götz Pfeiffer [ goetz(AT)dcs.st-and.ac.uk ] | 2024-10-13T00:17:32 | oeisdata/seq/A007/A007870.seq | bc447fbd56c19d109f3b4ef9190ae3f1 |
A007871 | Number of simple juggling patterns of n balls. | [
"1",
"1",
"3",
"12",
"66",
"420",
"3200",
"27144",
"258705",
"2704592",
"30898506",
"381922380",
"5090938955"
] | [
"nonn",
"hard"
] | 12 | 1 | 3 | null | null | Jack Boyce (jboyce(AT)physics.berkeley.edu) | 2015-08-13T19:43:58 | oeisdata/seq/A007/A007871.seq | 5aba6d5cd8026fd189eca7641f637227 |
A007872 | Sum of indices of windows of trapezoidal maps. | [
"1",
"1",
"1",
"4",
"9",
"27",
"89",
"304",
"944",
"3259",
"11081",
"38044",
"132921",
"467771",
"1650279",
"5907280",
"21183657",
"76488912",
"277631065",
"1012588940",
"3707127319",
"13632296219",
"50292158921",
"186165033296",
"691181554768",
"2573423459611"
] | [
"nonn",
"more"
] | 8 | 1 | 4 | [
"A007872",
"A007873"
] | null | Peter H. Borcherds (p.h.borcherds(AT)bham.ac.uk) | 2019-08-09T01:59:30 | oeisdata/seq/A007/A007872.seq | db0cc197a70c454008dfe5abe530780a |
A007873 | Indices of last windows of trapezoidal maps. | [
"1",
"1",
"3",
"5",
"11",
"21",
"45",
"85",
"179",
"341",
"717",
"1365",
"2867",
"5461",
"11475",
"21845",
"45875",
"87381",
"183597",
"349525",
"734003",
"1398101",
"2937555",
"5592405",
"11744051",
"22369621",
"47000877",
"89478485",
"187904819"
] | [
"nonn",
"more"
] | 7 | 1 | 3 | [
"A007872",
"A007873"
] | null | Peter H. Borcherds (phb(AT)phymat.bham.ac.uk) | 2019-08-09T01:59:25 | oeisdata/seq/A007/A007873.seq | 988c48549e1e36ccdbb631ad68656b81 |
A007874 | Distinct perimeter lengths of polygons with regularly spaced vertices. | [
"1",
"1",
"1",
"2",
"4",
"10",
"24",
"63",
"177",
"428",
"1230",
"2556",
"8202",
"18506",
"18162",
"119069"
] | [
"nonn"
] | 14 | 1 | 4 | [
"A007874",
"A030077"
] | null | Peter H. Borcherds (p.h.borcherds(AT)bham.ac.uk) | 2018-08-06T05:33:23 | oeisdata/seq/A007/A007874.seq | e495de80563da4ffeff110d0d4ef29d9 |
A007875 | Number of ways of writing n as p*q, with p <= q, gcd(p, q) = 1. | [
"1",
"1",
"1",
"1",
"1",
"2",
"1",
"1",
"1",
"2",
"1",
"2",
"1",
"2",
"2",
"1",
"1",
"2",
"1",
"2",
"2",
"2",
"1",
"2",
"1",
"2",
"1",
"2",
"1",
"4",
"1",
"1",
"2",
"2",
"2",
"2",
"1",
"2",
"2",
"2",
"1",
"4",
"1",
"2",
"2",
"2",
"1",
"2",
"1",
"2",
"2",
"2",
"1",
"2",
"2",
"2",
"2",
"2",
"1",
"4",
"1",
"2",
"2",
"1",
"2",
"4",
"1",
"2",
"2",
"4",
"1",
"2",
"1",
"2",
"2",
"2",
"2",
"4",
"1",
"2",
"1",
"2",
"1",
"4",
"2",
"2",
"2",
"2",
"1",
"4"
] | [
"nonn",
"nice",
"easy"
] | 78 | 1 | 6 | [
"A000005",
"A000010",
"A000079",
"A001221",
"A001620",
"A002110",
"A007875",
"A007955",
"A034444",
"A048105",
"A074962"
] | null | Victor Ufnarovski | 2023-09-09T06:49:26 | oeisdata/seq/A007/A007875.seq | 22d53fde622bb31fb4ce472287e60bf0 |
A007876 | a(2n-1) = n*a(2n-2), a(2n) = n*a(2n-1) + 1. | [
"1",
"2",
"4",
"9",
"27",
"82",
"328",
"1313",
"6565",
"32826",
"196956",
"1181737",
"8272159",
"57905114",
"463240912",
"3705927297",
"33353345673",
"300180111058",
"3001801110580",
"30018011105801",
"330198122163811",
"3632179343801922",
"43586152125623064"
] | [
"nonn",
"easy"
] | 2 | 1 | 2 | null | null | buzzard(AT)math.berkeley.edu (Kevin Buzzard) | 2003-05-16T03:00:00 | oeisdata/seq/A007/A007876.seq | 14997bb07f029c2e325053ac596f79b5 |
A007877 | Period 4 zigzag sequence: repeat [0,1,2,1]. | [
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0",
"1",
"2",
"1",
"0"
] | [
"nonn",
"easy",
"mult"
] | 116 | 0 | 3 | [
"A000035",
"A000749",
"A007877",
"A021913",
"A049310",
"A056594",
"A063886",
"A084099",
"A092184",
"A158289",
"A181878",
"A260686",
"A266313",
"A271751",
"A271832",
"A279313",
"A279319"
] | null | Christopher Lam Cham Kee (Topher(AT)CyberDude.Com) | 2024-08-03T07:10:24 | oeisdata/seq/A007/A007877.seq | bcffbdbd72229536a85ea277ba11b8df |
A007878 | Number of terms in discriminant of generic polynomial of degree n. | [
"1",
"2",
"5",
"16",
"59",
"246",
"1103",
"5247",
"26059",
"133881",
"706799",
"3815311",
"20979619",
"117178725",
"663316190",
"3798697446",
"21976689397"
] | [
"nonn",
"nice",
"hard",
"more"
] | 80 | 1 | 2 | null | null | reiner(AT)math.umn.edu | 2024-07-17T09:39:20 | oeisdata/seq/A007/A007878.seq | 61c9284639c9c540aac7e09c782a4207 |
A007879 | Chimes made by clock striking the hour and half-hour. | [
"1",
"1",
"1",
"2",
"1",
"3",
"1",
"4",
"1",
"5",
"1",
"6",
"1",
"7",
"1",
"8",
"1",
"9",
"1",
"10",
"1",
"11",
"1",
"12",
"1",
"1",
"1",
"2",
"1",
"3",
"1",
"4",
"1",
"5",
"1",
"6",
"1",
"7",
"1",
"8",
"1",
"9",
"1",
"10",
"1",
"11",
"1",
"12",
"1",
"1",
"1",
"2",
"1",
"3",
"1",
"4",
"1",
"5",
"1",
"6",
"1",
"7",
"1",
"8",
"1",
"9",
"1",
"10",
"1",
"11",
"1",
"12"
] | [
"nonn",
"easy"
] | 18 | 0 | 4 | [
"A007879",
"A010881",
"A057979"
] | null | Jan Wolitzky | 2022-03-27T13:38:20 | oeisdata/seq/A007/A007879.seq | 111eca1d8d855db82cef780465e31055 |
A007880 | Westminster chimes at 15-minute intervals (1). | [
"1",
"2",
"3",
"5",
"1",
"2",
"3",
"6",
"1",
"2",
"3",
"7",
"1",
"2",
"3",
"8",
"1",
"2",
"3",
"9",
"1",
"2",
"3",
"10",
"1",
"2",
"3",
"11",
"1",
"2",
"3",
"12",
"1",
"2",
"3",
"13",
"1",
"2",
"3",
"14",
"1",
"2",
"3",
"15",
"1",
"2",
"3",
"16",
"1",
"2",
"3",
"5",
"1",
"2",
"3",
"6",
"1",
"2",
"3",
"7",
"1",
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"3",
"8",
"1",
"2",
"3",
"9",
"1",
"2",
"3",
"10",
"1",
"2",
"3",
"11",
"1",
"2",
"3",
"12",
"1",
"2",
"3",
"13",
"1",
"2",
"3",
"14",
"1",
"2",
"3",
"15",
"1",
"2",
"3",
"16"
] | [
"nonn"
] | 9 | 0 | 2 | null | null | Colin Mallows | 2018-10-01T20:11:14 | oeisdata/seq/A007/A007880.seq | 8df5b3fdfc6e0db4e2398010c37f49f5 |
A007881 | Erroneous version of A001357 printed by mistake on back cover of Encyclopedia of Integer Sequences. | [
"1",
"2",
"4",
"8",
"18",
"71"
] | [
"dead"
] | 3 | 0 | 2 | null | null | null | 1999-12-11T03:00:00 | oeisdata/seq/A007/A007881.seq | caa4e6a52c9ec32cbb28be0418f043bc |
A007882 | Number of lattice points inside circle of radius n is 4(a(n)+n)-3. | [
"0",
"1",
"4",
"8",
"13",
"22",
"30",
"41",
"54",
"67",
"83",
"98",
"117",
"139",
"160",
"183",
"206",
"234",
"263",
"292",
"322",
"357",
"390",
"424",
"461",
"502",
"545",
"585",
"626",
"673",
"719",
"770",
"819",
"870",
"926",
"977",
"1034",
"1090",
"1153",
"1214",
"1272",
"1339",
"1404",
"1475",
"1543",
"1610",
"1683",
"1755",
"1832",
"1907",
"1990",
"2070",
"2147"
] | [
"nonn"
] | 17 | 1 | 3 | null | null | Randall L Rathbun | 2022-06-24T04:41:25 | oeisdata/seq/A007/A007882.seq | da9476c0dc5e9c567782a254d99f4ca6 |
A007883 | Westminster chimes at 15-minute intervals (2). | [
"4",
"8",
"12",
"17",
"4",
"8",
"12",
"18",
"4",
"8",
"12",
"19",
"4",
"8",
"12",
"20",
"4",
"8",
"12",
"21",
"4",
"8",
"12",
"22",
"4",
"8",
"12",
"23",
"4",
"8",
"12",
"24",
"4",
"8",
"12",
"25",
"4",
"8",
"12",
"26",
"4",
"8",
"12",
"27",
"4",
"8",
"12",
"28",
"4",
"8",
"12",
"17",
"4",
"8",
"12",
"18",
"4",
"8",
"12",
"19",
"4",
"8",
"12",
"20",
"4",
"8",
"12",
"21",
"4",
"8",
"12",
"22",
"4",
"8",
"12",
"23",
"4",
"8",
"12",
"24",
"4",
"8",
"12",
"25"
] | [
"nonn"
] | 8 | 1 | 1 | null | null | Colin Mallows | 2013-09-21T12:47:33 | oeisdata/seq/A007/A007883.seq | cbc05653769c90e8b8bd1cd7ae855369 |
A007884 | Chimes made by clock striking quarter-hours. | [
"1",
"2",
"3",
"1",
"1",
"2",
"3",
"2",
"1",
"2",
"3",
"3",
"1",
"2",
"3",
"4",
"1",
"2",
"3",
"5",
"1",
"2",
"3",
"6",
"1",
"2",
"3",
"7",
"1",
"2",
"3",
"8",
"1",
"2",
"3",
"9",
"1",
"2",
"3",
"10",
"1",
"2",
"3",
"11",
"1",
"2",
"3",
"12",
"1",
"2",
"3",
"1",
"1",
"2",
"3",
"2",
"1",
"2",
"3",
"3",
"1",
"2",
"3",
"4",
"1",
"2",
"3",
"5",
"1",
"2",
"3",
"6",
"1",
"2",
"3",
"7",
"1",
"2",
"3",
"8",
"1",
"2",
"3",
"9",
"1",
"2",
"3",
"10",
"1",
"2",
"3",
"11",
"1",
"2",
"3",
"12"
] | [
"nonn"
] | 12 | 0 | 2 | [
"A001492",
"A007879",
"A007880",
"A007883",
"A007884"
] | null | Colin Mallows | 2023-06-16T17:21:43 | oeisdata/seq/A007/A007884.seq | e45fc206487f0c709dd5d65f3d0f38a4 |
A007885 | Numbers n such that balanced sequences exist with n distinct elements. | [
"1",
"2",
"3",
"4",
"5",
"7",
"11",
"13",
"19",
"23",
"29",
"37",
"47",
"53",
"59",
"61",
"67",
"71",
"79",
"83",
"101",
"103",
"107",
"131",
"139",
"149",
"163",
"167",
"173",
"179",
"181",
"191",
"197",
"199",
"211",
"227",
"239",
"263",
"269",
"271",
"293",
"311",
"317",
"347",
"349",
"359",
"367",
"373",
"379",
"383",
"389",
"419",
"421",
"443",
"461",
"463",
"467"
] | [
"nonn",
"nice"
] | 18 | 1 | 2 | null | null | Colin Mallows | 2019-06-06T04:20:26 | oeisdata/seq/A007/A007885.seq | 804676c029c58322c03f94062890af9f |
A007886 | Number of cycles induced by iterating the Gray-coding of an n-bit number: a(n+1) = a(n) + ( 2^n / C_n), where C_n = least power of 2 >= n (C_n is the length of the cycle). | [
"1",
"2",
"3",
"4",
"6",
"8",
"12",
"20",
"36",
"52",
"84",
"148",
"276",
"532",
"1044",
"2068",
"4116",
"6164",
"10260",
"18452",
"34836",
"67604",
"133140",
"264212",
"526356",
"1050644",
"2099220",
"4196372",
"8390676",
"16779284",
"33556500",
"67110932",
"134219796",
"201328660",
"335546388",
"603981844"
] | [
"nonn"
] | 14 | 0 | 2 | [
"A007886",
"A054243"
] | null | Joe Culberson (joe(AT)cs.ualberta.ca) | 2024-03-07T07:26:32 | oeisdata/seq/A007/A007886.seq | 5d108abac8c0e7718e386b0102d94c06 |
A007887 | a(n) = Fibonacci(n) mod 9. | [
"0",
"1",
"1",
"2",
"3",
"5",
"8",
"4",
"3",
"7",
"1",
"8",
"0",
"8",
"8",
"7",
"6",
"4",
"1",
"5",
"6",
"2",
"8",
"1",
"0",
"1",
"1",
"2",
"3",
"5",
"8",
"4",
"3",
"7",
"1",
"8",
"0",
"8",
"8",
"7",
"6",
"4",
"1",
"5",
"6",
"2",
"8",
"1",
"0",
"1",
"1",
"2",
"3",
"5",
"8",
"4",
"3",
"7",
"1",
"8",
"0",
"8",
"8",
"7",
"6",
"4",
"1",
"5",
"6",
"2",
"8",
"1",
"0",
"1",
"1",
"2",
"3",
"5",
"8",
"4",
"3"
] | [
"nonn",
"easy"
] | 32 | 0 | 4 | null | null | N. J. A. Sloane. | 2025-01-05T19:51:34 | oeisdata/seq/A007/A007887.seq | c8c0c73a5a825b67330073b18724d0d7 |
A007888 | Euler characteristic of mapping class group Gamma_n. | [
"1",
"1",
"3",
"2",
"3",
"4",
"1",
"-6",
"45",
"-86",
"173",
"-100",
"2641",
"-48311",
"717766",
"-15527527",
"395694683",
"-11210796201",
"356923346235",
"-12694851400717",
"501010779605741",
"-21827969798073020",
"1044997258445975691",
"-54740156237911040100"
] | [
"sign"
] | 7 | 1 | 3 | null | null | Mira Bernstein | 2018-02-14T21:10:57 | oeisdata/seq/A007/A007888.seq | 512a809e568e2cd58d215bd0cc53980e |
A007889 | Number of intransitive (or alternating, or Stanley) trees: vertices are [0,n] and for no i<j<k are both (i,j) and (j,k) edges. | [
"1",
"1",
"2",
"7",
"36",
"246",
"2104",
"21652",
"260720",
"3598120",
"56010096",
"971055240",
"18558391936",
"387665694976",
"8787898861568",
"214868401724416",
"5636819806209792",
"157935254554567296",
"4707152127520549120",
"148704074888134683520",
"4963548160096887021056",
"174553183413968718996736"
] | [
"nonn",
"easy",
"nice"
] | 76 | 0 | 3 | [
"A007889",
"A029847",
"A038049",
"A138860",
"A283828",
"A323841"
] | null | Alexander Postnikov [ apost(AT)math.mit.edu ] | 2023-11-06T07:17:54 | oeisdata/seq/A007/A007889.seq | 39cbe6f254dd6b41f3f2a175f477085c |
A007890 | Summarize the previous term! (in decreasing order). | [
"1",
"11",
"21",
"1211",
"1231",
"131221",
"132231",
"232221",
"134211",
"14131231",
"14231241",
"24132231",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221",
"14233221"
] | [
"nonn",
"base",
"easy"
] | 22 | 1 | 2 | [
"A005150",
"A007890",
"A034003",
"A036058",
"A244112"
] | null | Mira Bernstein | 2020-08-20T01:18:18 | oeisdata/seq/A007/A007890.seq | e8471ba64a991940a2d6c37ed0a2cc9f |
A007891 | A Kutz sequence. | [
"1",
"4",
"1",
"4",
"9",
"4",
"9",
"16",
"9",
"16",
"25",
"16",
"25",
"36",
"25",
"36",
"49",
"36",
"49",
"64",
"49",
"64",
"81",
"64",
"81",
"100",
"81",
"100",
"121",
"100",
"121",
"144",
"121",
"144",
"169",
"144",
"169",
"196",
"169",
"196",
"225",
"196",
"225",
"256",
"225",
"256",
"289",
"256",
"289",
"324",
"289",
"324",
"361",
"324",
"361",
"400",
"361",
"400",
"441"
] | [
"nonn",
"easy"
] | 24 | 1 | 2 | null | null | N. J. A. Sloane | 2022-09-08T08:44:35 | oeisdata/seq/A007/A007891.seq | 39b1ec2cd643c290979c0334fa9941b5 |
A007892 | A Kutz sequence. | [
"1",
"4",
"9",
"1",
"4",
"9",
"16",
"4",
"9",
"16",
"25",
"9",
"16",
"25",
"36",
"16",
"25",
"36",
"49",
"25",
"36",
"49",
"64",
"36",
"49",
"64",
"81",
"49",
"64",
"81",
"100",
"64",
"81",
"100",
"121",
"81",
"100",
"121",
"144",
"100",
"121",
"144",
"169",
"121",
"144",
"169",
"196",
"144",
"169",
"196",
"225",
"169",
"196",
"225",
"256",
"196",
"225",
"256",
"289",
"225"
] | [
"nonn",
"easy"
] | 56 | 1 | 2 | null | null | N. J. A. Sloane | 2025-01-10T12:21:41 | oeisdata/seq/A007/A007892.seq | 9f9a178615d8838e7ad9d05b86cf6858 |
A007893 | A Kutz sequence. | [
"1",
"4",
"9",
"16",
"1",
"4",
"9",
"16",
"25",
"4",
"9",
"16",
"25",
"36",
"9",
"16",
"25",
"36",
"49",
"16",
"25",
"36",
"49",
"64",
"25",
"36",
"49",
"64",
"81",
"36",
"49",
"64",
"81",
"100",
"49",
"64",
"81",
"100",
"121",
"64",
"81",
"100",
"121",
"144",
"81",
"100",
"121",
"144",
"169",
"100",
"121",
"144",
"169",
"196",
"121",
"144",
"169",
"196",
"225",
"144",
"169",
"196"
] | [
"nonn",
"easy"
] | 27 | 1 | 2 | null | null | N. J. A. Sloane | 2022-09-08T08:44:35 | oeisdata/seq/A007/A007893.seq | db149f1e8d45a8213b6d023879643282 |
A007894 | Number of fullerenes with 2n vertices (or carbon atoms). | [
"1",
"0",
"1",
"1",
"2",
"3",
"6",
"6",
"15",
"17",
"40",
"45",
"89",
"116",
"199",
"271",
"437",
"580",
"924",
"1205",
"1812",
"2385",
"3465",
"4478",
"6332",
"8149",
"11190",
"14246",
"19151",
"24109",
"31924",
"39718",
"51592",
"63761",
"81738",
"99918",
"126409",
"153493",
"191839",
"231017",
"285914",
"341658",
"419013"
] | [
"nonn",
"easy",
"nice"
] | 66 | 10 | 5 | [
"A007894",
"A046880",
"A057210"
] | null | Boris Shraiman (boris(AT)physics.att.com), Gunnar Brinkmann and A. Dress (dress(AT)mathematik.uni-bielefeld.de) | 2025-02-16T08:32:31 | oeisdata/seq/A007/A007894.seq | 387ff58b2df93937ba9940f78eb08717 |
A007895 | Number of terms in the Zeckendorf representation of n (write n as a sum of non-consecutive distinct Fibonacci numbers). | [
"0",
"1",
"1",
"1",
"2",
"1",
"2",
"2",
"1",
"2",
"2",
"2",
"3",
"1",
"2",
"2",
"2",
"3",
"2",
"3",
"3",
"1",
"2",
"2",
"2",
"3",
"2",
"3",
"3",
"2",
"3",
"3",
"3",
"4",
"1",
"2",
"2",
"2",
"3",
"2",
"3",
"3",
"2",
"3",
"3",
"3",
"4",
"2",
"3",
"3",
"3",
"4",
"3",
"4",
"4",
"1",
"2",
"2",
"2",
"3",
"2",
"3",
"3",
"2",
"3",
"3",
"3",
"4",
"2",
"3",
"3",
"3",
"4",
"3",
"4",
"4",
"2",
"3",
"3",
"3",
"4",
"3",
"4",
"4",
"3",
"4",
"4",
"4",
"5",
"1",
"2",
"2",
"2",
"3",
"2",
"3",
"3",
"2",
"3",
"3",
"3",
"4",
"2",
"3",
"3"
] | [
"nonn",
"easy"
] | 168 | 0 | 5 | [
"A000045",
"A000120",
"A001950",
"A003714",
"A003849",
"A007015",
"A007016",
"A007895",
"A007953",
"A014417",
"A027941",
"A035514",
"A035515",
"A035516",
"A035517",
"A104324",
"A105446",
"A135817",
"A135818",
"A182535",
"A189920",
"A213676",
"A213911"
] | null | Felix Weinstein (wain(AT)ana.unibe.ch) and Clark Kimberling | 2025-03-24T07:38:31 | oeisdata/seq/A007/A007895.seq | cda1dc97704c093356e1700b409edbe3 |
A007896 | Psi_c(n), where Product_{k>1} 1/(1-1/k^s)^phi(k) = Sum_{k>0} psi_c(k)/k^s. | [
"1",
"1",
"2",
"3",
"4",
"4",
"6",
"7",
"9",
"8",
"10",
"12",
"12",
"12",
"16",
"18",
"16",
"19",
"18",
"24",
"24",
"20",
"22",
"32",
"30",
"24",
"34",
"36",
"28",
"40",
"30",
"42",
"40",
"32",
"48",
"60",
"36",
"36",
"48",
"64",
"40",
"60",
"42",
"60",
"76",
"44",
"46",
"86",
"63",
"66",
"64",
"72",
"52",
"82",
"80",
"96",
"72",
"56",
"58",
"128",
"60",
"60",
"114",
"104",
"96",
"100"
] | [
"nonn"
] | 54 | 1 | 3 | [
"A000010",
"A007896",
"A007897",
"A007898"
] | null | Felix Weinstein (wain(AT)ana.unibe.ch) | 2018-11-12T11:13:40 | oeisdata/seq/A007/A007896.seq | 85f0cd9e3f6003492142442471ec1395 |
A007897 | a(n) is multiplicative with a(2) = 1; a(4) = 2; a(2^i) = 2^(i-2)+2 if i>2; a(p^i) = 1+(p-1)*p^(i-1)/2 if prime p>2 and i>0. | [
"1",
"1",
"2",
"2",
"3",
"2",
"4",
"4",
"4",
"3",
"6",
"4",
"7",
"4",
"6",
"6",
"9",
"4",
"10",
"6",
"8",
"6",
"12",
"8",
"11",
"7",
"10",
"8",
"15",
"6",
"16",
"10",
"12",
"9",
"12",
"8",
"19",
"10",
"14",
"12",
"21",
"8",
"22",
"12",
"12",
"12",
"24",
"12",
"22",
"11",
"18",
"14",
"27",
"10",
"18",
"16",
"20",
"15",
"30",
"12",
"31",
"16",
"16",
"18",
"21",
"12",
"34",
"18",
"24",
"12",
"36",
"16",
"37",
"19",
"22",
"20",
"24",
"14",
"40",
"18",
"28"
] | [
"nonn",
"mult"
] | 40 | 1 | 3 | [
"A007896",
"A007897",
"A007898",
"A180783"
] | null | Felix Weinstein (wain(AT)ana.unibe.ch), Dec 11 1999 | 2023-11-09T08:53:25 | oeisdata/seq/A007/A007897.seq | 968cb942b668d2a334da3211dee723cf |
A007898 | a(n) = psi_c(n), where Product_{k>1} 1/(1-1/k^s)^A007897(k) = Sum_{k>0} psi_c(k)/k^s. | [
"1",
"1",
"2",
"3",
"3",
"4",
"4",
"7",
"7",
"6",
"6",
"12",
"7",
"8",
"12",
"16",
"9",
"15",
"10",
"18",
"16",
"12",
"12",
"32",
"17",
"14",
"22",
"24",
"15",
"30",
"16",
"34",
"24",
"18",
"24",
"48",
"19",
"20",
"28",
"48",
"21",
"40",
"22",
"36",
"45",
"24",
"24",
"78",
"32",
"37",
"36",
"42",
"27",
"54",
"36",
"64",
"40",
"30",
"30",
"96",
"31",
"32",
"60",
"78",
"42",
"60",
"34",
"54"
] | [
"nonn"
] | 30 | 1 | 3 | [
"A007896",
"A007897",
"A007898"
] | null | Felix Weinstein (wain(AT)ana.unibe.ch) | 2018-11-13T03:17:21 | oeisdata/seq/A007/A007898.seq | 9b40e03bbce50be367d40ffa47b2f1cd |
A007899 | Coordination sequence for hexagonal close-packing. | [
"1",
"12",
"44",
"96",
"170",
"264",
"380",
"516",
"674",
"852",
"1052",
"1272",
"1514",
"1776",
"2060",
"2364",
"2690",
"3036",
"3404",
"3792",
"4202",
"4632",
"5084",
"5556",
"6050",
"6564",
"7100",
"7656",
"8234",
"8832",
"9452",
"10092",
"10754",
"11436",
"12140",
"12864",
"13610",
"14376",
"15164",
"15972",
"16802",
"17652",
"18524",
"19416",
"20330",
"21264",
"22220"
] | [
"nonn",
"easy"
] | 54 | 0 | 2 | [
"A001845",
"A005893",
"A005894",
"A005897",
"A005898",
"A005899",
"A005901",
"A005902",
"A007202",
"A007899",
"A008137",
"A010001",
"A063489",
"A299254",
"A299255",
"A299256",
"A299257",
"A299258",
"A299259",
"A299260",
"A299261",
"A299262",
"A299263",
"A299264",
"A299265",
"A299266",
"A299267",
"A299268",
"A299269",
"A299272",
"A299273",
"A299274",
"A299275",
"A299276",
"A299277",
"A299278",
"A299279",
"A299280",
"A299281",
"A299282",
"A299283",
"A299284",
"A299285",
"A299286",
"A299287",
"A299288",
"A299289",
"A299290",
"A299291",
"A299292"
] | null | N. J. A. Sloane and J. H. Conway | 2024-03-14T23:26:35 | oeisdata/seq/A007/A007899.seq | 0e8855a99e8e2eeeb175c040004b18b4 |
A007900 | Coordination sequence for D_4 lattice. | [
"1",
"24",
"144",
"456",
"1056",
"2040",
"3504",
"5544",
"8256",
"11736",
"16080",
"21384",
"27744",
"35256",
"44016",
"54120",
"65664",
"78744",
"93456",
"109896",
"128160",
"148344",
"170544",
"194856",
"221376",
"250200",
"281424",
"315144",
"351456"
] | [
"nonn",
"easy"
] | 28 | 0 | 2 | [
"A007900",
"A103903"
] | null | N. J. A. Sloane and J. H. Conway | 2023-12-10T16:00:12 | oeisdata/seq/A007/A007900.seq | 9c839dbdbdbe6ada8e1ee9c92a3e2a9b |
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