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oeis

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1999-12-11 03:00:00
2025-04-28 00:58:08
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32
A007501
a(0) = 2; for n >= 0, a(n+1) = a(n)*(a(n)+1)/2.
[ "2", "3", "6", "21", "231", "26796", "359026206", "64449908476890321", "2076895351339769460477611370186681", "2156747150208372213435450937462082366919951682912789656986079991221" ]
[ "nonn", "easy" ]
59
0
1
[ "A000217", "A006893", "A007501", "A013589", "A050536", "A050542", "A050548", "A050909", "A117872", "A129440", "A275342" ]
[ "M0818" ]
N. J. A. Sloane, Robert G. Wilson v
2025-04-07T11:53:54
oeisdata/seq/A007/A007501.seq
162f24676a888a8d2b510aca6d820a5e
A007502
Les Marvin sequence: a(n) = F(n)+(n-1)*F(n-1), F() = Fibonacci numbers.
[ "1", "2", "4", "9", "17", "33", "61", "112", "202", "361", "639", "1123", "1961", "3406", "5888", "10137", "17389", "29733", "50693", "86204", "146246", "247577", "418299", "705479", "1187857", "1997018", "3352636", "5621097", "9412937", "15744681", "26307469", "43912648" ]
[ "nonn", "nice", "easy" ]
43
1
2
[ "A000045", "A007502", "A045925", "A088209", "A101220", "A109754" ]
[ "M1170" ]
N. J. A. Sloane, Robert G. Wilson v
2022-05-18T05:58:27
oeisdata/seq/A007/A007502.seq
6637ca9ca816c859a833e2b8f39f7c93
A007503
Number of subgroups of dihedral group: sigma(n) + d(n).
[ "2", "5", "6", "10", "8", "16", "10", "19", "16", "22", "14", "34", "16", "28", "28", "36", "20", "45", "22", "48", "36", "40", "26", "68", "34", "46", "44", "62", "32", "80", "34", "69", "52", "58", "52", "100", "40", "64", "60", "98", "44", "104", "46", "90", "84", "76", "50", "134", "60", "99", "76", "104", "56", "128", "76", "128", "84", "94", "62", "180", "64", "100", "110", "134" ]
[ "nonn" ]
62
1
1
[ "A000005", "A000203", "A007503", "A027750", "A037852", "A257644" ]
[ "M1321" ]
N. J. A. Sloane, Robert G. Wilson v
2022-07-21T07:41:37
oeisdata/seq/A007/A007503.seq
48dcf77257012c2a3a4a3d00222114b4
A007504
Sum of the first n primes.
[ "0", "2", "5", "10", "17", "28", "41", "58", "77", "100", "129", "160", "197", "238", "281", "328", "381", "440", "501", "568", "639", "712", "791", "874", "963", "1060", "1161", "1264", "1371", "1480", "1593", "1720", "1851", "1988", "2127", "2276", "2427", "2584", "2747", "2914", "3087", "3266", "3447", "3638", "3831", "4028", "4227", "4438", "4661", "4888" ]
[ "nonn", "nice" ]
229
0
2
[ "A000041", "A002110", "A007504", "A008472", "A013916", "A013918", "A014148", "A014150", "A034386", "A034387", "A038107", "A045345", "A050247", "A050248", "A068873", "A073619", "A111287", "A122989", "A178138", "A254784", "A254858" ]
[ "M1370" ]
N. J. A. Sloane, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007504.seq
8704c2f84b9b8497e9f717494539e235
A007505
Primes of form 3*2^n - 1.
[ "2", "5", "11", "23", "47", "191", "383", "6143", "786431", "51539607551", "824633720831", "26388279066623", "108086391056891903", "55340232221128654847", "226673591177742970257407", "59421121885698253195157962751", "30423614405477505635920876929023" ]
[ "nonn", "nice" ]
61
1
1
[ "A002235", "A007505", "A010051", "A039687", "A083329" ]
[ "M1395" ]
N. J. A. Sloane, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007505.seq
b3cd45790d019bf5508e4df043c39a84
A007506
Primes p with property that p divides the sum of all primes <= p.
[ "2", "5", "71", "369119", "415074643", "55691042365834801" ]
[ "nonn", "nice", "hard", "more" ]
79
1
1
[ "A007506", "A024011", "A028581", "A028582" ]
[ "M1554" ]
N. J. A. Sloane, Robert G. Wilson v
2024-09-08T12:11:56
oeisdata/seq/A007/A007506.seq
0e7f58b9b8c9d36014c10056241fedbe
A007507
Decimal expansion of 2^sqrt(2).
[ "2", "6", "6", "5", "1", "4", "4", "1", "4", "2", "6", "9", "0", "2", "2", "5", "1", "8", "8", "6", "5", "0", "2", "9", "7", "2", "4", "9", "8", "7", "3", "1", "3", "9", "8", "4", "8", "2", "7", "4", "2", "1", "1", "3", "1", "3", "7", "1", "4", "6", "5", "9", "4", "9", "2", "8", "3", "5", "9", "7", "9", "5", "9", "3", "3", "6", "4", "9", "2", "0", "4", "4", "6", "1", "7", "8", "7", "0", "5", "9", "5", "4", "8", "6", "7", "6", "0", "9", "1", "8", "0", "0", "0", "5", "1", "9", "6", "4", "1", "6", "9", "4", "1", "9", "8" ]
[ "cons", "nonn" ]
46
1
1
null
[ "M1560" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007507.seq
6b09db6f37a31906b7521403d79ec83d
A007508
Number of twin prime pairs below 10^n.
[ "2", "8", "35", "205", "1224", "8169", "58980", "440312", "3424506", "27412679", "224376048", "1870585220", "15834664872", "135780321665", "1177209242304", "10304195697298", "90948839353159", "808675888577436" ]
[ "nonn", "nice", "hard", "more", "changed" ]
117
1
1
[ "A001097", "A007508", "A152051", "A173081", "A181678", "A347278", "A347279" ]
[ "M1855" ]
N. J. A. Sloane, Robert G. Wilson v
2025-04-22T08:02:31
oeisdata/seq/A007/A007508.seq
b39336dd513aa00c254a2cfdebcd06c3
A007509
Numerator of Sum_{k=0..n} (-1)^k/(2*k+1).
[ "1", "2", "13", "76", "263", "2578", "36979", "33976", "622637", "11064338", "11757173", "255865444", "1346255081", "3852854518", "116752370597", "3473755390832", "3610501179557", "3481569435902", "133330680156299", "129049485078524", "5457995496252709", "227848175409504262", "234389556075339277" ]
[ "nonn", "easy", "nice", "frac" ]
54
0
2
[ "A007509", "A024199", "A142969", "A157142", "A166107", "A167576", "A167577", "A167578", "A167588", "A167589", "A352395" ]
[ "M2061" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007509.seq
d9fc9c78fab2a7c8a51849d9ddff4305
A007510
Single (or isolated or non-twin) primes: Primes p such that neither p-2 nor p+2 is prime.
[ "2", "23", "37", "47", "53", "67", "79", "83", "89", "97", "113", "127", "131", "157", "163", "167", "173", "211", "223", "233", "251", "257", "263", "277", "293", "307", "317", "331", "337", "353", "359", "367", "373", "379", "383", "389", "397", "401", "409", "439", "443", "449", "457", "467", "479", "487", "491", "499", "503", "509", "541", "547", "557", "563" ]
[ "nonn", "easy", "nice" ]
85
1
1
[ "A007510", "A010051", "A083370", "A102723", "A124582", "A134099", "A134100", "A134101" ]
[ "M2130" ]
N. J. A. Sloane, Robert G. Wilson v
2023-05-11T10:26:50
oeisdata/seq/A007/A007510.seq
75b672e649954943ab4b109170eac466
A007511
a(n) is the smallest number greater than a(n-1) that is expressible as the sum of two squares in more ways than a(n-1).
[ "2", "50", "325", "1105", "5525", "27625", "71825", "138125", "160225", "801125", "2082925", "4005625", "5928325", "29641625", "77068225", "148208125", "243061325", "1215306625", "3159797225", "6076533125", "12882250225", "53716552825", "64411251125", "167469252925", "322056255625", "785817263725" ]
[ "nonn" ]
14
1
1
[ "A007511", "A048610" ]
null
Gabriel Cunningham (gcasey(AT)mit.edu), Feb 29 2004
2017-12-20T23:27:39
oeisdata/seq/A007/A007511.seq
2ece41e1dcbe980d43ae8db09555eb5c
A007512
Primes of the form floor(e*10^k), i.e., formed by concatenation of an initial segment of the decimal expansion of e.
[ "2", "271", "2718281", "2718281828459045235360287471352662497757247093699959574966967627724076630353547594571" ]
[ "base", "nonn" ]
33
1
1
null
[ "M2184" ]
N. J. A. Sloane, Robert G. Wilson v, Simon Plouffe
2025-02-16T08:32:31
oeisdata/seq/A007/A007512.seq
ed6545c8eb48d8b6f5ec7032e56da3b8
A007513
a(n) = initial prime of n consecutive primes such that first and last have same digit sum.
[ "2", "523", "109", "79", "2", "13", "5", "127", "47", "17", "5", "127", "53", "17", "7", "67", "31", "37", "47", "37", "83", "11", "43", "19", "157", "2", "37", "5", "47", "5", "19", "67", "7", "29", "19", "53", "31", "73", "53", "29", "139", "13", "67", "83", "7", "47", "29", "17", "79", "7", "19", "37", "59", "43", "271", "19", "29", "181", "167", "59", "97", "5", "149", "7", "59", "337", "41", "53", "43", "127" ]
[ "base", "nonn", "easy", "nice", "look" ]
27
1
1
null
[ "M2186" ]
N. J. A. Sloane, Robert G. Wilson v
2023-02-27T13:35:05
oeisdata/seq/A007/A007513.seq
18730f67dc0b006bc157ebd7e9bb0652
A007514
Pi = Sum_{n >= 0} a(n)/n!.
[ "3", "0", "0", "0", "3", "1", "5", "6", "5", "0", "1", "4", "7", "8", "0", "6", "7", "10", "7", "10", "4", "10", "6", "16", "1", "11", "20", "3", "18", "12", "9", "13", "18", "21", "14", "34", "27", "11", "27", "33", "36", "18", "5", "18", "5", "23", "39", "1", "10", "42", "28", "17", "20", "51", "8", "42", "47", "0", "27", "23", "16", "52", "32", "52", "53", "24", "43", "61", "64", "18", "17", "11", "0", "53", "14", "62" ]
[ "nonn" ]
25
0
1
[ "A000796", "A004601", "A004608", "A007514", "A062964", "A068436", "A068440", "A075874" ]
[ "M2193" ]
N. J. A. Sloane, Robert G. Wilson v
2017-03-22T21:56:09
oeisdata/seq/A007/A007514.seq
f9e6ac3477a9eff14b9efbc3454399e5
A007515
Continued fraction for Wirsing's constant.
[ "0", "3", "3", "2", "2", "3", "13", "1", "174", "1", "1", "1", "2", "2", "2", "1", "1", "1", "2", "2", "1", "5", "6", "1", "1", "73", "1", "4", "2", "3", "8", "1", "15", "1", "1", "4", "5", "1", "1", "3", "2", "1", "2", "2", "5", "2", "1", "3", "1", "1", "1", "3", "1", "5", "1", "3", "1", "2", "1", "2", "1", "2", "34", "1", "1", "5", "1", "2", "7", "2", "1", "2", "4", "1", "1", "23", "15", "2", "1", "2", "3", "1", "1", "7", "1", "3", "2", "1", "8", "3", "2", "1", "1", "8", "93", "1", "8", "3" ]
[ "nonn", "cofr" ]
24
0
2
[ "A007515", "A038517" ]
[ "M2267" ]
N. J. A. Sloane, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007515.seq
4a95256a0364eed2ab11efe8c34e73c5
A007516
(2^2^...^2) (n times) + 1.
[ "1", "3", "5", "17", "65537" ]
[ "nonn" ]
16
0
2
[ "A004249", "A007516" ]
[ "M2504" ]
N. J. A. Sloane and Robert G. Wilson v
2015-08-26T01:06:36
oeisdata/seq/A007/A007516.seq
5e27a2aace2575d504e1788b975b0a2a
A007517
a(n) = phi(n) * (sigma(n) - n).
[ "0", "1", "2", "6", "4", "12", "6", "28", "24", "32", "10", "64", "12", "60", "72", "120", "16", "126", "18", "176", "132", "140", "22", "288", "120", "192", "234", "336", "28", "336", "30", "496", "300", "320", "312", "660", "36", "396", "408", "800", "40", "648", "42", "800", "792", "572", "46", "1216", "336", "860", "672", "1104", "52", "1188", "680" ]
[ "nonn", "easy" ]
25
1
3
[ "A000010", "A000203", "A001065", "A007517", "A059956", "A065465" ]
null
Walter Nissen
2023-12-04T01:34:41
oeisdata/seq/A007/A007517.seq
e249d90074cfa9544243826a7af7a82b
A007518
a(n) = floor(n*(n+2)*(2*n-1)/8).
[ "0", "3", "9", "21", "39", "66", "102", "150", "210", "285", "375", "483", "609", "756", "924", "1116", "1332", "1575", "1845", "2145", "2475", "2838", "3234", "3666", "4134", "4641", "5187", "5775", "6405", "7080", "7800", "8568", "9384", "10251", "11169", "12141", "13167", "14250", "15390", "16590", "17850", "19173", "20559", "22011", "23529", "25116", "26772", "28500", "30300" ]
[ "nonn", "easy" ]
32
1
2
[ "A007518", "A094953" ]
[ "M2776" ]
N. J. A. Sloane, Robert G. Wilson v
2022-09-08T08:44:35
oeisdata/seq/A007/A007518.seq
a3431ad38180802c181bfb6e90050a7d
A007519
Primes of form 8n+1, that is, primes congruent to 1 mod 8.
[ "17", "41", "73", "89", "97", "113", "137", "193", "233", "241", "257", "281", "313", "337", "353", "401", "409", "433", "449", "457", "521", "569", "577", "593", "601", "617", "641", "673", "761", "769", "809", "857", "881", "929", "937", "953", "977", "1009", "1033", "1049", "1097", "1129", "1153", "1193", "1201", "1217", "1249", "1289", "1297", "1321", "1361" ]
[ "nonn", "easy", "changed" ]
117
1
1
[ "A002144", "A007519", "A017077", "A038872", "A038873", "A038883", "A038889", "A042987", "A065091", "A068228", "A076339", "A094407", "A133870", "A139643", "A141111", "A141112", "A141123", "A142925", "A154264", "A208177", "A208178", "A242663" ]
[ "M5037" ]
N. J. A. Sloane, Robert G. Wilson v
2025-04-16T03:05:40
oeisdata/seq/A007/A007519.seq
01b9b7123f0c08fed423d53be0ed98ae
A007520
Primes == 3 (mod 8).
[ "3", "11", "19", "43", "59", "67", "83", "107", "131", "139", "163", "179", "211", "227", "251", "283", "307", "331", "347", "379", "419", "443", "467", "491", "499", "523", "547", "563", "571", "587", "619", "643", "659", "683", "691", "739", "787", "811", "827", "859", "883", "907", "947", "971", "1019", "1051", "1091", "1123", "1163", "1171", "1187" ]
[ "nonn", "easy" ]
73
1
1
[ "A007520", "A045339", "A294912" ]
[ "M2882" ]
N. J. A. Sloane, Robert G. Wilson v
2023-04-05T17:29:58
oeisdata/seq/A007/A007520.seq
cd3f28b7f60aa124895b2f1ea68b41d8
A007521
Primes of the form 8k + 5.
[ "5", "13", "29", "37", "53", "61", "101", "109", "149", "157", "173", "181", "197", "229", "269", "277", "293", "317", "349", "373", "389", "397", "421", "461", "509", "541", "557", "613", "653", "661", "677", "701", "709", "733", "757", "773", "797", "821", "829", "853", "877", "941", "997", "1013", "1021", "1061", "1069", "1093", "1109", "1117", "1181", "1213" ]
[ "nonn", "easy", "nice" ]
61
1
1
[ "A004770", "A007521", "A010051", "A045323" ]
[ "M3828" ]
N. J. A. Sloane, Robert G. Wilson v
2022-09-08T08:44:35
oeisdata/seq/A007/A007521.seq
e19a5b822a34883ce21f231a85155060
A007522
Primes of the form 8n+7, that is, primes congruent to -1 mod 8.
[ "7", "23", "31", "47", "71", "79", "103", "127", "151", "167", "191", "199", "223", "239", "263", "271", "311", "359", "367", "383", "431", "439", "463", "479", "487", "503", "599", "607", "631", "647", "719", "727", "743", "751", "823", "839", "863", "887", "911", "919", "967", "983", "991", "1031", "1039", "1063", "1087", "1103", "1151" ]
[ "nonn", "easy" ]
80
1
1
[ "A004771", "A007522", "A010051", "A014754", "A038872", "A038873", "A038883", "A038889", "A040098", "A065907", "A065908", "A068228", "A141111", "A141112", "A141123", "A141174" ]
[ "M4376" ]
N. J. A. Sloane, Robert G. Wilson v
2022-09-08T08:44:35
oeisdata/seq/A007/A007522.seq
7bee8e8ce72e80e4fd01beee97dec3bf
A007523
Primes in A092845 (decimal expansion of Pi written backwards).
[ "3", "13", "51413", "951413", "2951413", "53562951413", "979853562951413" ]
[ "base", "nonn" ]
31
1
1
[ "A005042", "A007523", "A011545", "A092845" ]
[ "M2966" ]
N. J. A. Sloane and Robert G. Wilson v
2025-03-26T11:30:47
oeisdata/seq/A007/A007523.seq
5e2770bffbaef4f57960ed09c074734e
A007524
Decimal expansion of log_10 2.
[ "3", "0", "1", "0", "2", "9", "9", "9", "5", "6", "6", "3", "9", "8", "1", "1", "9", "5", "2", "1", "3", "7", "3", "8", "8", "9", "4", "7", "2", "4", "4", "9", "3", "0", "2", "6", "7", "6", "8", "1", "8", "9", "8", "8", "1", "4", "6", "2", "1", "0", "8", "5", "4", "1", "3", "1", "0", "4", "2", "7", "4", "6", "1", "1", "2", "7", "1", "0", "8", "1", "8", "9", "2", "7", "4", "4", "2", "4", "5", "0", "9", "4", "8", "6", "9", "2", "7", "2", "5", "2", "1", "1", "8", "1", "8", "6", "1", "7", "2", "0", "4", "0", "6", "8", "4" ]
[ "nonn", "cons" ]
92
0
1
[ "A007524", "A104139", "A114490", "A114493", "A153268", "A153496", "A153620", "A153790", "A154182", "A154203", "A154368", "A154478", "A154580", "A154794", "A154860", "A154953", "A155062", "A155522", "A155677", "A155746", "A155830", "A155979" ]
[ "M2196" ]
N. J. A. Sloane
2025-03-22T13:33:04
oeisdata/seq/A007/A007524.seq
10efe5152b4e3b82c39373392899cbf1
A007525
Decimal expansion of log_2 e.
[ "1", "4", "4", "2", "6", "9", "5", "0", "4", "0", "8", "8", "8", "9", "6", "3", "4", "0", "7", "3", "5", "9", "9", "2", "4", "6", "8", "1", "0", "0", "1", "8", "9", "2", "1", "3", "7", "4", "2", "6", "6", "4", "5", "9", "5", "4", "1", "5", "2", "9", "8", "5", "9", "3", "4", "1", "3", "5", "4", "4", "9", "4", "0", "6", "9", "3", "1", "1", "0", "9", "2", "1", "9", "1", "8", "1", "1", "8", "5", "0", "7", "9", "8", "8", "5", "5", "2", "6", "6", "2", "2", "8", "9", "3", "5", "0", "6", "3", "4", "4", "4", "9", "6", "9", "9" ]
[ "nonn", "cons", "easy" ]
74
1
2
[ "A000670", "A002206", "A002207", "A007525", "A052882", "A091137", "A141417", "A165313" ]
[ "M3221" ]
N. J. A. Sloane
2024-12-30T11:27:09
oeisdata/seq/A007/A007525.seq
0d0d3659a4ea4e8b4f0631d34c6742e5
A007526
a(n) = n*(a(n-1) + 1), a(0) = 0.
[ "0", "1", "4", "15", "64", "325", "1956", "13699", "109600", "986409", "9864100", "108505111", "1302061344", "16926797485", "236975164804", "3554627472075", "56874039553216", "966858672404689", "17403456103284420", "330665665962403999", "6613313319248080000", "138879579704209680021", "3055350753492612960484" ]
[ "nonn", "easy", "changed" ]
190
0
3
[ "A000522", "A001339", "A007526", "A068424", "A128195", "A326659" ]
[ "M3505" ]
N. J. A. Sloane and Robert G. Wilson v
2025-04-16T10:57:55
oeisdata/seq/A007/A007526.seq
e3d6569ae9b13f38e54b85a785c5280a
A007527
Numbers that are not the sum of 4 hexagonal numbers.
[ "5", "10", "11", "20", "25", "26", "38", "39", "54", "65", "70", "114", "130" ]
[ "fini", "nonn", "full" ]
28
1
1
null
[ "M3793" ]
N. J. A. Sloane
2025-03-10T11:46:11
oeisdata/seq/A007/A007527.seq
9b430a3d2ade308d676a6561301f4730
A007528
Primes of the form 6k-1.
[ "5", "11", "17", "23", "29", "41", "47", "53", "59", "71", "83", "89", "101", "107", "113", "131", "137", "149", "167", "173", "179", "191", "197", "227", "233", "239", "251", "257", "263", "269", "281", "293", "311", "317", "347", "353", "359", "383", "389", "401", "419", "431", "443", "449", "461", "467", "479", "491", "503", "509", "521", "557", "563", "569", "587" ]
[ "nonn", "easy" ]
158
1
1
[ "A000040", "A001359", "A002144", "A002145", "A002476", "A003627", "A005384", "A007519", "A007520", "A007521", "A007522", "A007528", "A010051", "A016969", "A030430", "A030431", "A030432", "A030433", "A034694", "A038026", "A038700", "A040117", "A045380", "A045392", "A045437", "A045458", "A045471", "A045473", "A048265", "A057145", "A061237", "A061238", "A061239", "A061240", "A061241", "A061242", "A065091", "A068228", "A068229", "A068231", "A090187", "A117047", "A132231", "A140444", "A141849", "A141850", "A141851", "A141852", "A141853", "A141854", "A141855", "A141856", "A141857", "A214360", "A324076" ]
[ "M3809" ]
N. J. A. Sloane
2025-03-03T09:00:53
oeisdata/seq/A007/A007528.seq
45abda9a96c41fd5d23a1b75655a7aba
A007529
Prime triples: p; p+2 or p+4; p+6 all prime.
[ "5", "7", "11", "13", "17", "37", "41", "67", "97", "101", "103", "107", "191", "193", "223", "227", "277", "307", "311", "347", "457", "461", "613", "641", "821", "823", "853", "857", "877", "881", "1087", "1091", "1277", "1297", "1301", "1423", "1427", "1447", "1481", "1483", "1487", "1607", "1663", "1693", "1783", "1867", "1871", "1873", "1993", "1997" ]
[ "nonn" ]
40
1
1
[ "A007529", "A022004", "A022005", "A023201", "A031924", "A098414", "A098415", "A098416", "A098417", "A098424" ]
[ "M3760" ]
N. J. A. Sloane, Robert G. Wilson v
2022-04-07T10:44:53
oeisdata/seq/A007/A007529.seq
48599fb632ae34688f3f1dbbbacd1c4b
A007530
Prime quadruples: numbers k such that k, k+2, k+6, k+8 are all prime.
[ "5", "11", "101", "191", "821", "1481", "1871", "2081", "3251", "3461", "5651", "9431", "13001", "15641", "15731", "16061", "18041", "18911", "19421", "21011", "22271", "25301", "31721", "34841", "43781", "51341", "55331", "62981", "67211", "69491", "72221", "77261", "79691", "81041", "82721", "88811", "97841", "99131" ]
[ "nonn" ]
118
1
1
[ "A007530", "A007811", "A014561", "A120120", "A159910" ]
[ "M3816" ]
N. J. A. Sloane, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007530.seq
c0409cedbda19f7367bbeb310424a08e
A007531
a(n) = n*(n-1)*(n-2) (or n!/(n-3)!).
[ "0", "0", "0", "6", "24", "60", "120", "210", "336", "504", "720", "990", "1320", "1716", "2184", "2730", "3360", "4080", "4896", "5814", "6840", "7980", "9240", "10626", "12144", "13800", "15600", "17550", "19656", "21924", "24360", "26970", "29760", "32736", "35904", "39270", "42840", "46620", "50616", "54834", "59280", "63960", "68880" ]
[ "nonn", "easy" ]
200
0
4
[ "A000332", "A000389", "A000579", "A000580", "A000581", "A000582", "A002378", "A005563", "A007531", "A028896", "A084939", "A084940", "A084941", "A084942", "A084943", "A084944", "A161680" ]
[ "M4159" ]
N. J. A. Sloane, Robert G. Wilson v
2024-06-22T07:58:34
oeisdata/seq/A007/A007531.seq
7ea9f666f70b36bf4c901f03ce0bafb1
A007532
Handsome numbers: sum of positive powers of its digits; a(n) = Sum_{i=1..k} d[i]^e[i] where d[1..k] are the decimal digits of a(n), e[i] > 0.
[ "1", "2", "3", "4", "5", "6", "7", "8", "9", "24", "43", "63", "89", "132", "135", "153", "175", "209", "224", "226", "262", "264", "267", "283", "332", "333", "334", "357", "370", "371", "372", "373", "374", "375", "376", "377", "378", "379", "407", "445", "463", "518", "598", "629", "739", "794", "849", "935", "994", "1034" ]
[ "base", "nonn", "nice" ]
55
1
2
[ "A001694", "A003321", "A005188", "A005934", "A007532", "A014576", "A023052", "A046074", "A050240", "A050241", "A061862" ]
[ "M0487" ]
N. J. A. Sloane, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007532.seq
edfdc1321fb6c3066eb409ab4f5bdbbf
A007533
a(n) = (5*n + 1)^2 + 4*n + 1.
[ "2", "41", "130", "269", "458", "697", "986", "1325", "1714", "2153", "2642", "3181", "3770", "4409", "5098", "5837", "6626", "7465", "8354", "9293", "10282", "11321", "12410", "13549", "14738", "15977", "17266", "18605", "19994", "21433", "22922", "24461", "26050", "27689", "29378", "31117", "32906", "34745", "36634", "38573", "40562", "42601" ]
[ "nonn", "easy" ]
49
0
1
[ "A007533", "A154355" ]
[ "M2162" ]
N. J. A. Sloane, Robert G. Wilson v
2024-10-31T15:06:43
oeisdata/seq/A007/A007533.seq
6b4f5751629263b683e546da732ac13c
A007534
Positive even numbers that are not the sum of a pair of twin primes.
[ "2", "4", "94", "96", "98", "400", "402", "404", "514", "516", "518", "784", "786", "788", "904", "906", "908", "1114", "1116", "1118", "1144", "1146", "1148", "1264", "1266", "1268", "1354", "1356", "1358", "3244", "3246", "3248", "4204", "4206", "4208" ]
[ "nonn", "nice" ]
58
1
1
[ "A007534", "A051345", "A064409", "A129363", "A179825" ]
[ "M1306" ]
N. J. A. Sloane, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007534.seq
60a8eeb0cdb858e983f0e3b13ee89efe
A007535
Smallest pseudoprime ( > n ) to base n: smallest composite number m > n such that n^(m-1)-1 is divisible by m.
[ "4", "341", "91", "15", "124", "35", "25", "9", "28", "33", "15", "65", "21", "15", "341", "51", "45", "25", "45", "21", "55", "69", "33", "25", "28", "27", "65", "45", "35", "49", "49", "33", "85", "35", "51", "91", "45", "39", "95", "91", "105", "205", "77", "45", "76", "133", "65", "49", "66", "51", "65", "85", "65", "55", "63", "57", "65", "133", "87", "341", "91", "63", "341", "65", "112", "91" ]
[ "nonn", "nice", "easy" ]
43
1
1
[ "A002808", "A007535", "A071904", "A098653", "A098654" ]
[ "M5440" ]
N. J. A. Sloane, Mira Bernstein, Robert G. Wilson v
2025-02-16T08:32:31
oeisdata/seq/A007/A007535.seq
1ff335441c25d88fe66564e2cfde69b9
A007536
Numbers that are not the sum of 3 hexagonal numbers (probably finite).
[ "4", "5", "9", "10", "11", "14", "19", "20", "23", "24", "25", "26", "32", "33", "37", "38", "39", "41", "42", "48", "50", "53", "54", "55", "59", "63", "64", "65", "69", "70", "76", "77", "80", "83", "85", "86", "89", "99", "102", "104", "108", "110", "113", "114", "115", "116", "123", "124", "128", "129", "130", "131", "140", "143", "144", "145", "146", "152", "161", "162", "167" ]
[ "nonn", "fini", "nice" ]
31
1
1
[ "A000384", "A007536", "A118278", "A118279" ]
[ "M3244" ]
N. J. A. Sloane
2017-12-17T07:20:15
oeisdata/seq/A007/A007536.seq
503bb88781a38ddd26a07e999eb88a44
A007537
Number of proper covers of an n-set.
[ "0", "1", "45", "15913", "1073579193", "4611686005542975085", "85070591730234615801280047645054636261", "28948022309329048855892746252171976961956366698726387156269151989162886489297" ]
[ "nonn", "easy", "nice" ]
40
1
3
[ "A000371", "A003465", "A007537" ]
[ "M5287" ]
N. J. A. Sloane, Simon Plouffe
2025-02-16T08:32:31
oeisdata/seq/A007/A007537.seq
75d344f886a6557d29b16f10d0a4de94
A007538
A self-generating sequence: there are a(n) 3's between successive 2's.
[ "2", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3", "3", "3", "2", "3" ]
[ "nonn", "easy", "nice" ]
46
1
1
null
[ "M0432" ]
N. J. A. Sloane, Simon Plouffe
2024-02-05T11:36:40
oeisdata/seq/A007/A007538.seq
b7728aaea07f9ec557b61b1799eae568
A007539
a(n) = first n-fold perfect (or n-multiperfect) number.
[ "1", "6", "120", "30240", "14182439040", "154345556085770649600", "141310897947438348259849402738485523264343544818565120000" ]
[ "nonn", "nice", "more" ]
86
1
2
[ "A000396", "A005820", "A007539", "A007691", "A025487", "A027687", "A046060", "A046061", "A072002", "A227765", "A227766", "A227767", "A227768", "A227769", "A349747" ]
[ "M4297" ]
N. J. A. Sloane
2023-04-03T10:36:09
oeisdata/seq/A007/A007539.seq
0dd8f74e60eac7ebb706c137a443c2a9
A007540
Wilson primes: primes p such that (p-1)! == -1 (mod p^2).
[ "5", "13", "563" ]
[ "nonn", "hard", "more", "bref", "nice", "changed" ]
140
1
1
[ "A007540", "A007619", "A157249", "A157250", "A377266" ]
[ "M3838" ]
N. J. A. Sloane
2025-04-25T04:27:40
oeisdata/seq/A007/A007540.seq
a35707bf19aee5abbb7208985e84f490
A007541
Incrementally largest terms in the continued fraction for Pi-2 (cf. A001203).
[ "1", "7", "15", "292", "436", "20776", "78629", "179136", "528210", "12996958", "878783625", "5408240597", "5916686112", "9448623833", "9787547328", "52662113289" ]
[ "nonn" ]
47
1
2
[ "A000796", "A001203", "A007541", "A033089", "A033090" ]
[ "M4351" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007541.seq
92c67e82caafed837c6bc20c5d2dcdb6
A007542
Successive integers produced by Conway's PRIMEGAME.
[ "2", "15", "825", "725", "1925", "2275", "425", "390", "330", "290", "770", "910", "170", "156", "132", "116", "308", "364", "68", "4", "30", "225", "12375", "10875", "28875", "25375", "67375", "79625", "14875", "13650", "2550", "2340", "1980", "1740", "4620", "4060", "10780", "12740", "2380", "2184", "408", "152" ]
[ "easy", "nonn", "look", "nice" ]
77
1
1
[ "A007542", "A007546", "A007547", "A183132", "A202138", "A203363" ]
[ "M2084" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007542.seq
851fc35ce2cebad59b05b66e274e796b
A007543
Frequency of n-th largest distance in N times N grid, N > n.
[ "2", "8", "12", "8", "16", "24", "20", "32", "18", "24", "40", "48", "28", "48", "60", "32", "32", "56", "72", "80", "36", "64", "84", "96", "50", "40", "72", "96", "112", "120", "44", "80", "108", "128", "140", "72", "48", "88", "120", "144", "160", "168", "52", "96", "132", "160", "180", "192", "98", "56", "104", "144", "176", "200", "216", "224", "60" ]
[ "nonn" ]
19
1
1
[ "A007543", "A007544" ]
[ "M1826" ]
N. J. A. Sloane
2018-01-08T02:38:41
oeisdata/seq/A007/A007543.seq
4534d35db4daaa7ff1a558afe1f0933e
A007544
Frequency of n-th largest distance in N times N times N grid, N > n.
[ "4", "24", "36", "48", "48", "144", "32", "60", "192", "108", "144", "72", "240", "288", "192", "216", "84", "288", "360", "432", "576", "108", "96", "336", "432", "288", "480", "720", "384", "432", "108", "384", "504", "336", "576", "300", "864", "960", "540", "576", "120", "432", "576", "384", "672", "1728", "1152", "1248", "1440", "256" ]
[ "nonn" ]
17
1
1
[ "A007543", "A007544" ]
[ "M3595" ]
N. J. A. Sloane
2021-12-26T21:43:45
oeisdata/seq/A007/A007544.seq
28b33fae3c5b523b11d6bfb89e925fdf
A007545
Number of chess games with n plies (another version).
[ "1", "20", "400", "8902", "197742", "4897256", "120921506", "3284294545", "88867026005" ]
[ "fini", "nonn", "hard" ]
24
0
2
[ "A006494", "A007545", "A048987" ]
[ "M5100" ]
Ken Thompson (ken(AT)google.com)
2025-02-16T08:32:31
oeisdata/seq/A007/A007545.seq
b4e8b171b8d4e4e901eda8de36ec8ccb
A007546
Number of steps to compute n-th prime in PRIMEGAME (fast version).
[ "19", "69", "280", "707", "2363", "3876", "8068", "11319", "19201", "36866", "45551", "75224", "101112", "117831", "152025", "215384", "293375", "327020", "428553", "507519", "555694", "700063", "808331", "989526", "1273490", "1434366", "1530213", "1710923", "1818254", "2019962", "2833089", "3104685", "3546320", "3720785" ]
[ "easy", "nonn", "nice" ]
36
1
1
[ "A007542", "A007546", "A007547" ]
[ "M5074" ]
N. J. A. Sloane
2021-12-17T11:04:42
oeisdata/seq/A007/A007546.seq
096cd1a8dd15fe61aabe6c6db3691e47
A007547
Number of steps to compute n-th prime in PRIMEGAME (slow version).
[ "19", "69", "281", "710", "2375", "3893", "8102", "11361", "19268", "36981", "45680", "75417", "101354", "118093", "152344", "215797", "293897", "327571", "429229", "508284", "556494", "701008", "809381", "990746", "1274952", "1435957", "1531854", "1712701", "1820085", "2021938", "2835628", "3107393", "3549288", "3723821" ]
[ "easy", "nonn", "nice" ]
43
1
1
[ "A006530", "A007542", "A007546", "A007547", "A034785" ]
[ "M5075" ]
N. J. A. Sloane
2024-06-12T14:10:27
oeisdata/seq/A007/A007547.seq
e465867f7784a6673bc90b811ece8579
A007548
Shifts 3 places left under exponentiation.
[ "1", "1", "1", "1", "2", "5", "15", "53", "213", "961", "4808", "26405", "157965", "1022573", "7122441", "53118601", "422362118", "3566967917", "31887812715", "300848966213", "2987359924149", "31143724848889", "340113005563268", "3882897830626949", "46254432194746377", "573938743829923349", "7406289665830324689" ]
[ "nonn", "eigen" ]
33
1
5
null
[ "M1485" ]
N. J. A. Sloane.
2021-07-16T08:25:32
oeisdata/seq/A007/A007548.seq
03db36e371d1614c69f6039a4d3ba88d
A007549
Number of increasing rooted connected graphs where every block is a complete graph.
[ "1", "1", "3", "14", "89", "716", "6967", "79524", "1041541", "15393100", "253377811", "4596600004", "91112351537", "1959073928124", "45414287553455", "1129046241331316", "29965290866974493", "845605519848379436", "25282324544244718411", "798348403914242674980", "26549922456617388029641" ]
[ "nonn", "eigen", "nice" ]
54
1
3
[ "A007549", "A007563", "A029768", "A030019", "A035051", "A035053", "A078341", "A264436" ]
[ "M2977" ]
N. J. A. Sloane
2025-02-26T08:48:39
oeisdata/seq/A007/A007549.seq
69025531938c17d8372423ab1495e895
A007550
Natural numbers exponentiated twice.
[ "1", "4", "20", "127", "967", "8549", "85829", "962308", "11895252", "160475855", "2343491207", "36795832297", "617662302441", "11031160457672", "208736299803440", "4169680371133507", "87648971646028515", "1933298000313801349", "44633323736412392093", "1076069422794010119112" ]
[ "nonn", "nice" ]
37
1
2
null
[ "M3568" ]
N. J. A. Sloane
2018-06-25T15:29:30
oeisdata/seq/A007/A007550.seq
230454ef332326cc2039f6082ba02157
A007551
Shifts left when Moebius transformation applied twice.
[ "1", "1", "-1", "-3", "-4", "-6", "-2", "-4", "3", "6", "16", "14", "33", "31", "37", "51", "56", "54", "55", "53", "45", "55", "25", "23", "-17", "-8", "-72", "-79", "-135", "-137", "-235", "-237", "-343", "-369", "-479", "-463", "-622", "-624", "-732", "-792", "-898", "-900", "-1056", "-1058", "-1144", "-1234", "-1282", "-1284", "-1428", "-1423", "-1418", "-1524", "-1467", "-1469", "-1425", "-1445", "-1262", "-1366" ]
[ "sign", "look", "eigen" ]
24
1
4
null
[ "M2313" ]
N. J. A. Sloane.
2017-05-07T22:12:01
oeisdata/seq/A007/A007551.seq
2dcb569a2ea17ea1c296a167f6770d71
A007552
Exponentiation of Fibonacci numbers.
[ "1", "3", "10", "42", "204", "1127", "6924", "46704", "342167", "2700295", "22799218", "204799885", "1947993126", "19540680497", "206001380039", "2275381566909", "26261810071925", "315969045744894", "3954454344433658", "51382626410402336", "691956435942841207" ]
[ "nonn" ]
33
1
2
[ "A006701", "A007552", "A256180" ]
[ "M2860" ]
N. J. A. Sloane.
2017-06-11T07:48:53
oeisdata/seq/A007/A007552.seq
5012005632ac4a20786c1e33f9430c3e
A007553
Logarithmic transform of Fibonacci numbers.
[ "1", "1", "1", "1", "7", "5", "85", "335", "1135", "15245", "13475", "717575", "4256825", "29782325", "525045275", "243258625", "56809006625", "415670267875", "5068080417875", "104229929847625", "60861649495625", "20784245979986875", "169274937975443125", "3318579283890780625", "75028912866554839375" ]
[ "nonn" ]
56
1
5
null
[ "M4329" ]
N. J. A. Sloane
2021-12-26T22:10:20
oeisdata/seq/A007/A007553.seq
eb6a5a0c2abcaa0105f916208946832c
A007554
Unique attractor for (RIGHT then MOBIUS) transform.
[ "1", "1", "0", "-1", "-2", "-3", "-3", "-4", "-3", "-3", "-1", "-2", "3", "2", "5", "8", "12", "11", "17", "16", "21", "25", "26", "25", "30", "32", "29", "32", "32", "31", "30", "29", "21", "23", "11", "17", "5", "4", "-13", "-15", "-28", "-29", "-52", "-53", "-76", "-78", "-104", "-105", "-142", "-139", "-168", "-179", "-209", "-210", "-253", "-249", "-278", "-294" ]
[ "sign", "nice", "eigen", "look" ]
44
1
5
[ "A003238", "A007554", "A008683", "A027750", "A054525" ]
[ "M0434" ]
N. J. A. Sloane
2024-12-07T08:02:13
oeisdata/seq/A007/A007554.seq
a18a8b2d64e7b0ced662e492f8a3f3e9
A007555
Number of standard paths of length n in composition poset.
[ "1", "1", "2", "6", "23", "107", "586", "3690", "26245", "207997", "1817090", "17345358", "179595995", "2004596903", "23992185226", "306497734962", "4162467826729", "59882101858777", "909688617178178", "14551535460258966", "244477068964113407" ]
[ "nonn" ]
36
0
3
null
[ "M1667" ]
Simon Plouffe
2019-09-22T08:02:56
oeisdata/seq/A007/A007555.seq
67aa52ddfa5a342855dac8c680408901
A007556
Number of 8-ary trees with n vertices.
[ "1", "1", "8", "92", "1240", "18278", "285384", "4638348", "77652024", "1329890705", "23190029720", "410333440536", "7349042994488", "132969010888280", "2426870706415800", "44627576949364104", "826044435409399800", "15378186970730687400" ]
[ "nonn", "nice", "eigen" ]
84
0
3
[ "A007318", "A007556", "A062993", "A130564", "A234461", "A234462", "A234463", "A234464", "A234465", "A234466", "A234467" ]
[ "M4565" ]
N. J. A. Sloane
2024-02-05T08:24:40
oeisdata/seq/A007/A007556.seq
c4e82c1b06a1680ff0910d40f56f7311
A007557
Shifts left when inverse Moebius transform applied twice.
[ "1", "1", "3", "5", "10", "12", "24", "26", "43", "52", "78", "80", "133", "135", "189", "219", "295", "297", "428", "430", "584", "642", "804", "806", "1100", "1123", "1395", "1494", "1856", "1858", "2428", "2430", "2977", "3143", "3739", "3811", "4790", "4792", "5654", "5930", "7072", "7074", "8656" ]
[ "nonn", "nice", "eigen" ]
38
1
3
[ "A000005", "A003238", "A007554", "A007557", "A038045", "A038046", "A070965", "A127170" ]
[ "M2458" ]
N. J. A. Sloane
2019-05-11T18:32:08
oeisdata/seq/A007/A007557.seq
441cc6c296f9e90ae34852e33635e83e
A007558
Shifts 2 places left when e.g.f. is squared.
[ "1", "1", "1", "2", "4", "10", "30", "100", "380", "1600", "7400", "37400", "204600", "1205600", "7612000", "51260000", "366784000", "2778820000", "22222332000", "187067320000", "1653461480000", "15310662400000", "148217381840000", "1497226615280000", "15754506226800000", "172407188412800000" ]
[ "nonn", "nice", "eigen" ]
50
0
4
null
[ "M1230" ]
N. J. A. Sloane
2023-10-30T00:13:27
oeisdata/seq/A007/A007558.seq
7565164d77e89480d2878c6aa8f6dccc
A007559
Triple factorial numbers (3*n-2)!!! with leading 1 added.
[ "1", "1", "4", "28", "280", "3640", "58240", "1106560", "24344320", "608608000", "17041024000", "528271744000", "17961239296000", "664565853952000", "26582634158080000", "1143053268797440000", "52580450364682240000", "2576442067869429760000", "133974987529210347520000", "7368624314106569113600000" ]
[ "nonn", "nice", "easy" ]
181
0
3
[ "A001147", "A004987", "A007559", "A007661", "A007696", "A008544", "A008548", "A032031", "A035469", "A051141", "A095660", "A107716", "A129116", "A286718", "A336633" ]
[ "M3627" ]
N. J. A. Sloane
2024-12-30T02:07:29
oeisdata/seq/A007/A007559.seq
ee18b282c22ae2766f160746a51dcf13
A007560
Number of planted identity trees where non-root, non-leaf nodes an even distance from root are of degree 2.
[ "1", "1", "1", "1", "2", "2", "4", "6", "10", "17", "29", "51", "89", "159", "284", "512", "930", "1692", "3101", "5698", "10515", "19464", "36143", "67296", "125622", "235050", "440756", "828142", "1558955", "2939761", "5552744", "10504222", "19899760", "37750091", "71704061", "136361602", "259618770", "494821629", "944074665" ]
[ "nonn", "nice", "eigen" ]
36
1
5
[ "A007560", "A007562", "A316074" ]
[ "M0325" ]
N. J. A. Sloane
2021-12-16T22:15:45
oeisdata/seq/A007/A007560.seq
ba1d42b78aa44138bbdaf6ae55be35d2
A007561
Number of asymmetric rooted connected graphs where every block is a complete graph.
[ "0", "1", "1", "1", "3", "6", "16", "43", "120", "339", "985", "2892", "8606", "25850", "78347", "239161", "734922", "2271085", "7054235", "22010418", "68958139", "216842102", "684164551", "2165240365", "6871792256", "21865189969", "69737972975", "222915760126", "714001019626", "2291298553660", "7366035776888" ]
[ "nonn", "nice", "eigen" ]
34
0
5
[ "A007561", "A007563", "A035079", "A035081", "A316101" ]
[ "M2591" ]
N. J. A. Sloane
2021-12-16T22:15:59
oeisdata/seq/A007/A007561.seq
9f08eddd0ae3b6b26940868ea2898a21
A007562
Number of planted trees where non-root, non-leaf nodes an even distance from root are of degree 2.
[ "1", "1", "1", "2", "3", "6", "10", "20", "36", "72", "137", "275", "541", "1098", "2208", "4521", "9240", "19084", "39451", "82113", "171240", "358794", "753460", "1587740", "3353192", "7100909", "15067924", "32044456", "68272854", "145730675", "311575140", "667221030", "1430892924", "3072925944", "6607832422", "14226665499" ]
[ "nonn", "nice", "eigen" ]
58
1
4
[ "A000081", "A000837", "A004111", "A007560", "A007562", "A144018", "A289509", "A316470", "A316473", "A316475" ]
[ "M0773" ]
N. J. A. Sloane
2021-06-11T18:25:47
oeisdata/seq/A007/A007562.seq
5d8bd2e6856a2c5243d89ef3903a59df
A007563
Number of rooted connected graphs where every block is a complete graph.
[ "0", "1", "1", "3", "8", "25", "77", "258", "871", "3049", "10834", "39207", "143609", "532193", "1990163", "7503471", "28486071", "108809503", "417862340", "1612440612", "6248778642", "24309992576", "94905791606", "371691137827", "1459935388202", "5749666477454" ]
[ "nonn", "nice", "eigen" ]
56
0
4
[ "A007549", "A007563", "A030019", "A035051", "A035052", "A035053", "A144042", "A245566" ]
[ "M2751" ]
N. J. A. Sloane
2018-08-05T20:44:50
oeisdata/seq/A007/A007563.seq
90a783803b09be6bd9747fd410562bf5
A007564
Shifts left when INVERT transform applied thrice.
[ "1", "1", "4", "19", "100", "562", "3304", "20071", "124996", "793774", "5120632", "33463102", "221060008", "1473830308", "9904186192", "67015401391", "456192667396", "3122028222934", "21467769499864", "148246598341018", "1027656663676600", "7148588698592956", "49884553176689584" ]
[ "nonn", "nice", "eigen" ]
130
0
3
[ "A007564", "A047891", "A054872" ]
[ "M3556" ]
N. J. A. Sloane
2024-08-03T04:17:10
oeisdata/seq/A007/A007564.seq
ab3e5e736abcf1322103d79d5b3acc5e
A007565
Number of Go games with n moves.
[ "1", "362", "130683", "47046243", "16889859363", "6046709375131" ]
[ "nonn", "fini", "nice", "hard" ]
28
0
2
[ "A007565", "A048289" ]
[ "M5447" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007565.seq
fef09d531c830805afc0ac8b8ecc4131
A007566
a(n+1) = (2n+3)*a(n) - 2n*a(n-1) + 8n, a(0) = 1, a(1) = 3.
[ "1", "3", "21", "151", "1257", "12651", "151933", "2127231", "34035921", "612646867", "12252937701", "269564629863", "6469551117241", "168208329048891", "4709833213369677", "141294996401091151", "4521439884834917793", "153728956084387206051", "5534242419037939419061", "210301211923441697925687" ]
[ "nonn", "easy" ]
14
0
2
[ "A007566", "A010844" ]
[ "M3081" ]
N. J. A. Sloane
2021-12-26T21:40:24
oeisdata/seq/A007/A007566.seq
841e8fc756fc8e40d9f6ac6de49d6cde
A007567
Knopfmacher expansion of 1/2: a(n+1) = a(n-1)(a(n)+1)-1.
[ "-3", "-2", "2", "5", "11", "59", "659", "38939", "25661459", "999231590939", "25641740502411581459", "25622037156669717708454796390939", "656993627914472375437286314449293585586011019581459", "16833515146119850260546015286782697097805280607642932235667159033564811666316390939" ]
[ "sign", "easy", "nice" ]
21
0
1
null
[ "M2242" ]
N. J. A. Sloane, Jeffrey Shallit
2016-03-06T12:39:07
oeisdata/seq/A007/A007567.seq
dd8bc665430b1bdeb70e75eb4fdf9603
A007568
Knopfmacher expansion of 2/3: a(n+1) = a(n-1)(a(n)+1)-1.
[ "4", "3", "3", "11", "35", "395", "13859", "5474699", "75873867299", "415386585433442699", "31516986660961757816520267299", "13091733472248265157675672660811061946713442699", "412611989213715130181341760777978491100613491478334525377331427960520267299" ]
[ "nonn" ]
20
0
1
null
[ "M3209" ]
N. J. A. Sloane, Jeffrey Shallit
2016-03-06T12:38:30
oeisdata/seq/A007/A007568.seq
714e39616f95feffc650980cf130e63f
A007569
Number of nodes in regular n-gon with all diagonals drawn.
[ "1", "2", "3", "5", "10", "19", "42", "57", "135", "171", "341", "313", "728", "771", "1380", "1393", "2397", "1855", "3895", "3861", "6006", "5963", "8878", "7321", "12675", "12507", "17577", "17277", "23780", "16831", "31496", "30945", "40953", "40291", "52395", "47017", "66082", "65019", "82290", "80921", "101311", "84883", "123453", "121485" ]
[ "easy", "nonn", "nice" ]
50
1
2
[ "A001006", "A006533", "A006561", "A006600", "A007569", "A007678", "A054726" ]
[ "M0724" ]
N. J. A. Sloane, Bjorn Poonen (poonen(AT)math.princeton.edu)
2025-02-16T08:32:31
oeisdata/seq/A007/A007569.seq
9934748aa0c569dd78d556d1a68ee5f7
A007570
a(n) = F(F(n)), where F is a Fibonacci number.
[ "0", "1", "1", "1", "2", "5", "21", "233", "10946", "5702887", "139583862445", "1779979416004714189", "555565404224292694404015791808", "2211236406303914545699412969744873993387956988653", "2746979206949941983182302875628764119171817307595766156998135811615145905740557" ]
[ "nonn", "nice", "easy" ]
127
0
5
[ "A000045", "A001622", "A005371", "A007570", "A058051", "A094214" ]
[ "M1537" ]
N. J. A. Sloane, Robert G. Wilson v
2025-01-05T19:51:34
oeisdata/seq/A007/A007570.seq
0857b83829d4b3cdd051c9f88b854a27
A007571
a(n) = largest prime factor of n^n + 1.
[ "2", "5", "7", "257", "521", "97", "911", "673", "530713", "27961", "58367", "2227777", "79301", "176597", "142111", "67280421310721", "45957792327018709121", "33388093", "870542161121", "4406613081041681", "22864311556633", "73194743542229", "1522029233", "27250359649" ]
[ "nonn", "hard" ]
44
1
1
[ "A006486", "A006530", "A007571", "A014566", "A056790" ]
[ "M1343" ]
N. J. A. Sloane, Robert G. Wilson v
2023-10-10T06:21:33
oeisdata/seq/A007/A007571.seq
5459255e4f184a4c999d3c292740d6c7
A007572
Generalization of the golden ratio (expansion of (5-13x)/((1+x)(1-4x))).
[ "5", "2", "26", "86", "362", "1430", "5738", "22934", "91754", "366998", "1468010", "5872022", "23488106", "93952406", "375809642", "1503238550", "6012954218", "24051816854", "96207267434", "384829069718", "1539316278890", "6157265115542", "24629060462186" ]
[ "nonn" ]
22
0
1
null
[ "M3735" ]
Simon Plouffe and N. J. A. Sloane, Robert G. Wilson v
2017-12-20T23:28:26
oeisdata/seq/A007/A007572.seq
c6491938b6747f56a891b4a398c33f28
A007573
a(n) is the number of base numbers with 2n+1 digits in the asymmetric families of palindromic squares.
[ "1", "2", "5", "6", "9", "10", "10", "15", "15", "16", "18", "24", "18", "26", "24", "30", "27", "33", "28", "40", "33", "40", "35", "48", "37", "50", "42", "53", "45", "58", "46", "64", "50", "64", "54", "72", "55", "73", "60", "78", "63", "82", "63", "88", "69", "88", "72", "95", "73", "98", "78", "102", "80", "106", "82", "112", "87", "111", "90", "120", "91", "122", "95", "126", "99", "130", "100", "135" ]
[ "nonn", "base" ]
29
3
2
[ "A002778", "A002779", "A007573", "A060087", "A060088" ]
[ "M1319" ]
Simon Plouffe, N. J. A. Sloane, Robert G. Wilson v
2023-11-04T14:01:02
oeisdata/seq/A007/A007573.seq
d9594fd1591c7d8811f44e488fdf53c5
A007574
Patterns in a dual ring.
[ "1", "3", "7", "15", "31", "60", "113", "207", "373", "663", "1167", "2038", "3537", "6107", "10499", "17983", "30703", "52272", "88769", "150407", "254321", "429223", "723167", "1216490", "2043361", "3427635", "5742463", "9609327", "16062463", "26821668", "44744657", "74576703", "124192237", "206650167", "343594479" ]
[ "nonn", "easy" ]
35
1
2
[ "A000045", "A007574" ]
[ "M2653" ]
Simon Plouffe and N. J. A. Sloane, Robert G. Wilson v
2025-01-05T19:51:34
oeisdata/seq/A007/A007574.seq
2a655a4a2671d29434d6b884de6833aa
A007575
Number of stable towers of 2 X 2 LEGO blocks.
[ "1", "3", "7", "19", "53", "149", "419", "1191", "3403", "9755", "28077", "81097", "234861", "681697", "1982723", "5777375", "16861521", "49281525", "144222987", "422566835", "1239423303", "3638872529", "10693065215", "31448140529", "92558787745", "272612601065", "803448576111" ]
[ "nonn" ]
32
0
2
[ "A007575", "A007576" ]
[ "M2675" ]
Simon Plouffe and N. J. A. Sloane, Robert G. Wilson v
2020-02-24T21:56:10
oeisdata/seq/A007/A007575.seq
7120e582c048c42ba8475e39bbe218bf
A007576
Number of solutions to k_1 + 2*k_2 + ... + n*k_n = 0, where k_i are from {-1,0,1}, i=1..n.
[ "1", "1", "1", "3", "7", "15", "35", "87", "217", "547", "1417", "3735", "9911", "26513", "71581", "194681", "532481", "1464029", "4045117", "11225159", "31268577", "87404465", "245101771", "689323849", "1943817227", "5494808425", "15568077235", "44200775239", "125739619467" ]
[ "easy", "nonn" ]
87
0
4
[ "A007575", "A007576", "A039826", "A063865" ]
[ "M2656" ]
Simon Plouffe, Robert G. Wilson v and Vladeta Jovovic
2023-10-30T00:47:48
oeisdata/seq/A007/A007576.seq
e22dc31449dc423b2d425d21d08bfe12
A007577
Number of chess games with n plies (another version).
[ "1", "20", "400", "8902", "197281", "4865577", "119057155", "3194833218" ]
[ "hard", "fini", "nonn" ]
13
0
2
[ "A007577", "A048987" ]
null
Johan Boye (jb(AT)sectra.se)
2020-02-25T02:09:57
oeisdata/seq/A007/A007577.seq
96ba25e4fbad97be4121980a2c07b08f
A007578
Number of Young tableaux of height <= 7.
[ "1", "1", "2", "4", "10", "26", "76", "232", "763", "2611", "9415", "35135", "136335", "544623", "2242618", "9463508", "40917803", "180620411", "813405580", "3728248990", "17377551032", "82232982872", "394742985974", "1919885633178", "9453682648281", "47086636037601", "237071351741426", "1205689994416252" ]
[ "nonn" ]
51
0
3
[ "A007578", "A182172" ]
[ "M1219" ]
Simon Plouffe
2020-02-25T02:09:38
oeisdata/seq/A007/A007578.seq
87f92d24a5daeaf2501205bd8344e0db
A007579
Number of Young tableaux of height <= 6.
[ "1", "1", "2", "4", "10", "26", "76", "231", "756", "2556", "9096", "33231", "126060", "488488", "1948232", "7907185", "32831370", "138321690", "593610420", "2579109780", "11377862340", "50726936820", "229078351992", "1043999256966", "4810194384348", "22340617618860", "104742353862360", "494547143860035" ]
[ "nonn" ]
61
0
3
[ "A007579", "A182172" ]
[ "M1217" ]
Simon Plouffe
2021-09-23T05:47:30
oeisdata/seq/A007/A007579.seq
43df88e84c71ba538cf418e4c4076c08
A007580
Number of Young tableaux of height <= 8.
[ "1", "1", "2", "4", "10", "26", "76", "232", "764", "2619", "9486", "35596", "139392", "562848", "2352064", "10092160", "44546320", "201158620", "930213752", "4387327088", "21115314916", "103386386516", "515097746072", "2605341147472", "13378787264584", "69622529312665", "367161088308490", "1959294979429380" ]
[ "nonn" ]
44
0
3
[ "A007580", "A182172" ]
[ "M1220" ]
Simon Plouffe
2017-12-20T23:28:58
oeisdata/seq/A007/A007580.seq
aa21399cc071df8f836bbb7265b28de6
A007581
a(n) = (2^n+1)*(2^n+2)/6.
[ "1", "2", "5", "15", "51", "187", "715", "2795", "11051", "43947", "175275", "700075", "2798251", "11188907", "44747435", "178973355", "715860651", "2863377067", "11453377195", "45813246635", "183252462251", "733008800427", "2932033104555", "11728128223915", "46912504507051", "187650001250987" ]
[ "nonn", "easy", "nice" ]
153
0
2
[ "A000392", "A007051", "A007581", "A028401", "A056272", "A056273", "A056450", "A060919", "A278984" ]
[ "M1479" ]
Simon Plouffe and N. J. A. Sloane
2022-09-08T08:44:35
oeisdata/seq/A007/A007581.seq
6572890e5efe22503317386cc96292da
A007582
a(n) = 2^(n-1)*(1+2^n).
[ "1", "3", "10", "36", "136", "528", "2080", "8256", "32896", "131328", "524800", "2098176", "8390656", "33558528", "134225920", "536887296", "2147516416", "8590000128", "34359869440", "137439215616", "549756338176", "2199024304128", "8796095119360", "35184376283136", "140737496743936", "562949970198528" ]
[ "nonn", "easy", "nice" ]
146
0
2
[ "A000035", "A000079", "A000217", "A000225", "A000392", "A006516", "A007051", "A007582", "A011782", "A028243", "A032263", "A049773", "A049775", "A060531", "A081186", "A081187", "A081188", "A081189", "A081190", "A081192", "A102573", "A134308" ]
[ "M2849" ]
Simon Plouffe
2024-11-06T21:52:50
oeisdata/seq/A007/A007582.seq
ddac2e5c5d1968624e0b8f13488c953a
A007583
a(n) = (2^(2*n + 1) + 1)/3.
[ "1", "3", "11", "43", "171", "683", "2731", "10923", "43691", "174763", "699051", "2796203", "11184811", "44739243", "178956971", "715827883", "2863311531", "11453246123", "45812984491", "183251937963", "733007751851", "2932031007403", "11728124029611", "46912496118443", "187649984473771", "750599937895083" ]
[ "nonn", "easy" ]
230
0
2
[ "A000978", "A000979", "A002450", "A004171", "A005578", "A006054", "A006356", "A007051", "A007302", "A007583", "A081294", "A083065", "A083066", "A083884", "A124400", "A124401", "A127936", "A127955", "A127956", "A127957", "A127958" ]
[ "M2895" ]
Simon Plouffe
2025-02-19T11:53:38
oeisdata/seq/A007/A007583.seq
603d0ec3dd53d025fba6a30dd3d37445
A007584
9-gonal (or enneagonal) pyramidal numbers: a(n) = n*(n+1)*(7*n-4)/6.
[ "0", "1", "10", "34", "80", "155", "266", "420", "624", "885", "1210", "1606", "2080", "2639", "3290", "4040", "4896", "5865", "6954", "8170", "9520", "11011", "12650", "14444", "16400", "18525", "20826", "23310", "25984", "28855", "31930", "35216", "38720", "42449", "46410", "50610", "55056", "59755", "64714", "69940", "75440", "81221" ]
[ "nonn", "easy" ]
56
0
3
[ "A007584", "A093564", "A237616" ]
[ "M4695" ]
N. J. A. Sloane, R. K. Guy
2022-09-08T08:44:35
oeisdata/seq/A007/A007584.seq
c44e5b67ef79a8ee7812ac2cd8969aa3
A007585
10-gonal (or decagonal) pyramidal numbers: a(n) = n*(n + 1)*(8*n - 5)/6.
[ "0", "1", "11", "38", "90", "175", "301", "476", "708", "1005", "1375", "1826", "2366", "3003", "3745", "4600", "5576", "6681", "7923", "9310", "10850", "12551", "14421", "16468", "18700", "21125", "23751", "26586", "29638", "32915", "36425", "40176", "44176", "48433", "52955", "57750" ]
[ "nonn", "easy", "nice" ]
64
0
3
[ "A000384", "A001107", "A007585", "A093565", "A237616" ]
[ "M4791" ]
N. J. A. Sloane, R. K. Guy
2022-09-08T08:44:35
oeisdata/seq/A007/A007585.seq
446be4a12e8c70a53b654af1c2aec587
A007586
11-gonal (or hendecagonal) pyramidal numbers: n*(n+1)*(3*n-2)/2.
[ "0", "1", "12", "42", "100", "195", "336", "532", "792", "1125", "1540", "2046", "2652", "3367", "4200", "5160", "6256", "7497", "8892", "10450", "12180", "14091", "16192", "18492", "21000", "23725", "26676", "29862", "33292", "36975", "40920", "45136", "49632", "54417", "59500", "64890", "70596", "76627", "82992", "89700", "96760", "104181" ]
[ "nonn", "easy", "nice" ]
53
0
3
[ "A007586", "A051682", "A093644", "A237616" ]
[ "M4835" ]
N. J. A. Sloane, R. K. Guy
2022-09-08T08:44:35
oeisdata/seq/A007/A007586.seq
0b83f4ca997f4f51f184416da0cdc668
A007587
12-gonal (or dodecagonal) pyramidal numbers: n(n+1)(10n-7)/6.
[ "0", "1", "13", "46", "110", "215", "371", "588", "876", "1245", "1705", "2266", "2938", "3731", "4655", "5720", "6936", "8313", "9861", "11590", "13510", "15631", "17963", "20516", "23300", "26325", "29601", "33138", "36946", "41035", "45415", "50096", "55088", "60401", "66045", "72030", "78366", "85063", "92131", "99580", "107420", "115661" ]
[ "nonn", "easy", "nice" ]
56
0
3
[ "A000566", "A007587", "A051624", "A093645", "A237616" ]
[ "M4895" ]
N. J. A. Sloane, R. K. Guy
2022-09-08T08:44:35
oeisdata/seq/A007/A007587.seq
d30038e66cc8d681ac1e1d14ecca1433
A007588
Stella octangula numbers: a(n) = n*(2*n^2 - 1).
[ "0", "1", "14", "51", "124", "245", "426", "679", "1016", "1449", "1990", "2651", "3444", "4381", "5474", "6735", "8176", "9809", "11646", "13699", "15980", "18501", "21274", "24311", "27624", "31225", "35126", "39339", "43876", "48749", "53970", "59551", "65504", "71841", "78574", "85715", "93276", "101269", "109706", "118599", "127960" ]
[ "nonn", "easy", "nice" ]
151
0
3
[ "A000447", "A000578", "A001653", "A003154", "A004006", "A004068", "A004126", "A004188", "A004466", "A004467", "A005900", "A006003", "A006527", "A007588", "A062025", "A063521", "A063522", "A063523", "A135503", "A229384", "A267017" ]
[ "M4932" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007588.seq
f5631fb71c5ce367734551cc21e58d5a
A007589
Dodecahedral surface numbers: a(0)=0, a(1)=1, a(2)=20, thereafter 2*((3*n-7)^2 + 21).
[ "0", "1", "20", "50", "92", "170", "284", "434", "620", "842", "1100", "1394", "1724", "2090", "2492", "2930", "3404", "3914", "4460", "5042", "5660", "6314", "7004", "7730", "8492", "9290", "10124", "10994", "11900", "12842", "13820", "14834", "15884", "16970", "18092", "19250" ]
[ "nonn", "easy" ]
42
0
3
null
[ "M5083" ]
N. J. A. Sloane, R. K. Guy
2024-04-25T09:34:14
oeisdata/seq/A007/A007589.seq
b7c956a4c35f30f2a13f6ed4ca647d0b
A007590
a(n) = floor(n^2/2).
[ "0", "0", "2", "4", "8", "12", "18", "24", "32", "40", "50", "60", "72", "84", "98", "112", "128", "144", "162", "180", "200", "220", "242", "264", "288", "312", "338", "364", "392", "420", "450", "480", "512", "544", "578", "612", "648", "684", "722", "760", "800", "840", "882", "924", "968", "1012", "1058", "1104", "1152", "1200", "1250", "1300", "1352", "1404" ]
[ "nonn", "easy" ]
197
0
3
[ "A000212", "A000290", "A000982", "A002620", "A007590", "A030511", "A033429", "A033436", "A033437", "A033438", "A033439", "A052928", "A056827", "A056834", "A056838", "A056865", "A080476", "A094953", "A101037", "A118013", "A118015", "A130519", "A182834", "A184535", "A212964", "A245575" ]
[ "M1090" ]
N. J. A. Sloane, R. K. Guy
2025-02-16T08:32:31
oeisdata/seq/A007/A007590.seq
562335635ee66e70b2153b398c0ec326
A007591
Numbers k such that k^2 + 4 is prime.
[ "1", "3", "5", "7", "13", "15", "17", "27", "33", "35", "37", "45", "47", "57", "65", "67", "73", "85", "87", "95", "97", "103", "115", "117", "125", "135", "137", "147", "155", "163", "167", "177", "183", "193", "203", "207", "215", "217", "233", "235", "243", "245", "253", "255", "265", "267", "275", "277", "287", "293", "303", "307", "313", "317", "347", "357", "373", "375" ]
[ "nonn", "easy" ]
43
1
2
[ "A005574", "A007591", "A049422", "A067201", "A078402", "A114269", "A114270", "A114271", "A114272", "A114273", "A114274", "A114275" ]
[ "M2416" ]
N. J. A. Sloane, R. K. Guy
2025-02-16T08:32:31
oeisdata/seq/A007/A007591.seq
e6255a7bd2fdc59064729b27a128ec2d
A007592
Hyperperfect numbers: k = m*(sigma(k) - k - 1) + 1 for some m > 1.
[ "21", "301", "325", "697", "1333", "1909", "2041", "2133", "3901", "10693", "16513", "19521", "24601", "26977", "51301", "96361", "130153", "159841", "163201", "176661", "214273", "250321", "275833", "296341", "306181", "389593", "486877", "495529", "542413", "808861", "1005421", "1005649", "1055833", "1063141", "1232053" ]
[ "nonn", "nice" ]
46
1
1
[ "A007592", "A034897" ]
[ "M5113" ]
N. J. A. Sloane
2025-02-16T08:32:31
oeisdata/seq/A007/A007592.seq
d44d1d93e6cbad78db0ccb45ca7e6562
A007593
2-hyperperfect numbers: n = 2*(sigma(n) - n - 1) + 1.
[ "21", "2133", "19521", "176661", "129127041" ]
[ "nonn", "hard", "more" ]
104
1
1
[ "A000203", "A000396", "A007593", "A014682", "A028499", "A028500", "A028501", "A028502", "A034916", "A220290", "A337342" ]
[ "M5121" ]
N. J. A. Sloane, David W. Wilson
2025-02-16T08:32:31
oeisdata/seq/A007/A007593.seq
5c5c11b2313a54ec2a125f1c42647833
A007594
Smallest n-hyperperfect number: m such that m=n(sigma(m)-m-1)+1; or 0 if no such number exists.
[ "6", "21", "325", "1950625" ]
[ "nonn" ]
18
1
1
null
[ "M4150" ]
N. J. A. Sloane.
2016-03-12T12:35:39
oeisdata/seq/A007/A007594.seq
6bdfc23b2cfe24273dec4737bfa33490
A007595
a(n) = C_n / 2 if n is even or ( C_n + C_((n-1)/2) ) / 2 if n is odd, where C = Catalan numbers (A000108).
[ "1", "1", "3", "7", "22", "66", "217", "715", "2438", "8398", "29414", "104006", "371516", "1337220", "4847637", "17678835", "64823110", "238819350", "883634026", "3282060210", "12233141908", "45741281820", "171529836218", "644952073662", "2430973304732", "9183676536076", "34766775829452", "131873975875180" ]
[ "nonn", "easy" ]
84
1
3
[ "A000108", "A000150", "A003444", "A007123", "A007595", "A047996", "A072506", "A073201", "A334843" ]
[ "M2681" ]
N. J. A. Sloane
2022-12-31T01:33:08
oeisdata/seq/A007/A007595.seq
6d7cd8a71145126c31da9f73533aab4e
A007596
Erroneous version of A226909.
[ "1", "2", "4", "44", "164", "616" ]
[ "dead" ]
12
0
2
null
[ "M1302" ]
null
2014-04-18T02:49:27
oeisdata/seq/A007/A007596.seq
f4f0b8c549f13bc95fb09447f85583c1
A007597
Strobogrammatic primes.
[ "11", "101", "181", "619", "16091", "18181", "19861", "61819", "116911", "119611", "160091", "169691", "191161", "196961", "686989", "688889", "1008001", "1068901", "1160911", "1180811", "1190611", "1191611", "1681891", "1690691", "1880881", "1881881", "1898681", "1908061", "1960961", "1990661", "6081809", "6100019", "6108019" ]
[ "base", "nonn" ]
32
1
1
[ "A000787", "A007597" ]
[ "M4800" ]
N. J. A. Sloane, Robert G. Wilson v
2023-04-03T10:36:09
oeisdata/seq/A007/A007597.seq
914ce02ef2e7f9288450d39ba7018dfc
A007598
Squared Fibonacci numbers: a(n) = F(n)^2 where F = A000045.
[ "0", "1", "1", "4", "9", "25", "64", "169", "441", "1156", "3025", "7921", "20736", "54289", "142129", "372100", "974169", "2550409", "6677056", "17480761", "45765225", "119814916", "313679521", "821223649", "2149991424", "5628750625", "14736260449", "38580030724", "101003831721", "264431464441", "692290561600" ]
[ "nonn", "easy", "nice", "changed" ]
268
0
4
[ "A000032", "A000045", "A001254", "A001622", "A001654", "A006498", "A007598", "A047946", "A056570", "A059260", "A061646", "A065885", "A074677", "A079291", "A080097", "A103323", "A105393", "A175395" ]
[ "M3364" ]
N. J. A. Sloane, Robert G. Wilson v
2025-04-14T10:13:05
oeisdata/seq/A007/A007598.seq
b77385fdd60695088851627a49e3981e
A007599
a(n+1) = a(n)+a(a(a(..(n-1)..))), depth [ n/2 ].
[ "1", "0", "1", "1", "1", "1", "2", "3", "4", "5", "5", "5", "6", "7", "8", "9", "9", "9", "10", "11", "11", "11", "12", "13", "14", "15", "15", "15", "16", "17", "17", "17", "18", "19", "19", "19", "20", "21", "21", "21", "22", "23", "24", "25", "25", "25", "26", "27", "27", "27", "28", "29", "29", "29", "30", "31", "31", "31", "32", "33", "33", "33", "34", "35", "35", "35", "36", "37", "37", "37", "38", "39", "39", "39", "40" ]
[ "nonn", "nice", "easy" ]
17
0
7
null
[ "M0455" ]
N. J. A. Sloane, Mira Bernstein, Robert G. Wilson v
2016-08-28T18:23:35
oeisdata/seq/A007/A007599.seq
c457f974281cf69b2b8fc5ebbc49eb10
A007600
Minimal number of subsets in a separating family for a set of n elements.
[ "0", "2", "3", "4", "5", "5", "6", "6", "6", "7", "7", "7", "8", "8", "8", "8", "8", "8", "9", "9", "9", "9", "9", "9", "9", "9", "9", "10", "10", "10", "10", "10", "10", "10", "10", "10", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "11", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12", "12" ]
[ "nonn", "easy", "nice" ]
55
1
2
[ "A000792", "A007600", "A007601" ]
[ "M0456" ]
N. J. A. Sloane, Robert G. Wilson v, and Mira Bernstein
2025-02-16T08:32:31
oeisdata/seq/A007/A007600.seq
03eb9bade27e02d361a9da47a4fbc9e1