cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-7 of 7 results.

A001255 Squares of partition numbers.

Original entry on oeis.org

1, 1, 4, 9, 25, 49, 121, 225, 484, 900, 1764, 3136, 5929, 10201, 18225, 30976, 53361, 88209, 148225, 240100, 393129, 627264, 1004004, 1575025, 2480625, 3833764, 5934096, 9060100, 13823524, 20839225, 31404816, 46812964, 69705801, 102880449, 151536100
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

Formula

a(n) = A000041(n)^2.
a(n) ~ exp(2*Pi*sqrt(2*n/3)) / (48*n^2). - Vaclav Kotesovec, Dec 01 2015
Sum_{n>=1} 1/a(n) = A200089. - Amiram Eldar, May 01 2021
a(n) = A006907(n) + A051748(n) + A051749(n). - R. J. Mathar, Mar 09 2022
a(n) = [(x*y)^n] Product_{k>=1} 1 / ((1 - x^k) * (1 - y^k)). - Ilya Gutkovskiy, Apr 24 2025

Extensions

Extended by Ray Chandler, Nov 14 2005

A051748 Number of character table entries of the symmetric group S_n which are < 0.

Original entry on oeis.org

0, 1, 2, 7, 13, 34, 72, 137, 249, 524, 953, 1679, 3106, 5270, 9398, 15666, 26284, 43409, 72861, 115940, 189476, 297929, 476904, 743094, 1174624, 1782368, 2787256, 4196505, 6413986, 9645485, 14553197, 21483398, 32243250, 47165359, 69606943
Offset: 1

Views

Author

JOHN MCKAY (mckay(AT)cs.concordia.ca), Dec 08 1999

Keywords

Crossrefs

Programs

Extensions

More terms from Eric M. Schmidt, Jul 14 2012

A051749 Number of character table entries of the symmetric group S_n which are > 0.

Original entry on oeis.org

1, 3, 6, 14, 26, 58, 98, 194, 344, 652, 1165, 2020, 3552, 6077, 10362, 17080, 28570, 46836, 77045, 122013, 198461, 310602, 494008, 767237, 1205391, 1828252, 2846995, 4277605, 6520106, 9795470, 14738493, 21750402, 32582580, 47614253, 70213289
Offset: 1

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Author

JOHN MCKAY (mckay(AT)cs.concordia.ca), Dec 08 1999

Keywords

Crossrefs

Programs

Formula

A006907(n) + A051748(n) + a(n) = A001255(n). - R. J. Mathar, Mar 09 2022

Extensions

More terms from Eric M. Schmidt, Jul 14 2012

A006908 Number of nonzero elements in the character table of the symmetric group S_n.

Original entry on oeis.org

1, 4, 8, 21, 39, 92, 170, 331, 593, 1176, 2118, 3699, 6658, 11347, 19760, 32746, 54854, 90245, 149906, 237953, 387937, 608531, 970912, 1510331, 2380015, 3610620, 5634251, 8474110, 12934092, 19440955, 29291690, 43233800, 64825830, 94779612, 139820232
Offset: 1

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Author

Keywords

Comments

John McKay (email to N. J. A. Sloane, Apr 23 2013) observes that A061256 and A006908 coincide for a surprising number of terms, and asks for an explanation. - N. J. A. Sloane, May 19 2013

References

  • J. McKay, personal communication to N. J. A. Sloane, circa 1991.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • GAP
    A006908 := n -> Sum(Irr(CharacterTable("Symmetric", n)), chi -> Number(chi, x->x<>0)); # Eric M. Schmidt, Jul 13 2012, revised Sep 05 2012
  • Mathematica
    a[n_] := Count[FiniteGroupData[{"SymmetricGroup", n}, "CharacterTable"], k_ /; k != 0, 2]; Array[a, 10] (* Jean-François Alcover, Oct 21 2016 *)

Extensions

More terms from Eric M. Schmidt, Jul 13 2012

A274691 Number of odd entries in the character table of the symmetric group S_n.

Original entry on oeis.org

1, 1, 4, 7, 19, 33, 77, 135, 218, 392, 798, 1312, 2381, 4107, 6639, 11722, 15869, 26333, 45115, 69168, 106213, 170710, 244042, 384991, 592859, 895944, 1326012, 2055454, 2884762, 4466493, 6553384, 9798596, 13336991, 20192347, 28680574, 41695293, 59766105, 86344867
Offset: 0

Views

Author

Richard Stanley, Jul 02 2016

Keywords

Examples

			For n = 2, all four character values are 1 or -1, so a(2) = 4.
		

Crossrefs

Programs

  • Maple
    with(combinat):
    a:= n-> add(`if`(i[]::odd, 1, 0), i=entries(character(n))):
    seq(a(n), n=0..15);  # Alois P. Heinz, Jul 10 2016

Extensions

More terms from Alois P. Heinz, Jul 10 2016
Further terms from Miller (2019) added by N. J. A. Sloane, Jul 07 2020

A335686 Number of even entries in the character table of the symmetric group S_n.

Original entry on oeis.org

0, 0, 0, 2, 6, 16, 44, 90, 266, 508, 966, 1824, 3548, 6094, 11586, 19254, 37492, 61876, 103110, 170932, 286916, 456554, 759962, 1190034, 1887766, 2937820, 4608084, 7004646, 10938762, 16372732, 24851432, 37014368, 56368810, 82688102, 122855526, 179808396, 263406424
Offset: 0

Views

Author

N. J. A. Sloane, Jul 07 2020

Keywords

Crossrefs

A061220 Least entry in character table of the symmetric group S_n.

Original entry on oeis.org

1, -1, -1, -1, -2, -3, -6, -16, -36, -91, -224, -768, -2420, -7854, -22815, -73008, -292864, -1223040, -5002998, -17592960, -67184000, -279734796, -1183614120, -5844883968, -29448258840, -124619677182, -573333075000, -2764864302200, -13664438287500
Offset: 1

Views

Author

Ola Veshta (olaveshta(AT)my-deja.com), May 30 2001

Keywords

Comments

The maximal value in the character table is the maximal degree of an irreducible representation of S_n and this is in sequence A003040.

Examples

			a(3) = -1 because the character table of S_3 is / 1 1 1 / 1 1 -1 / 2 -1 0 /.
		

Crossrefs

Programs

  • GAP
    A061220 := n -> Minimum(List(Irr(CharacterTable("Symmetric", n)), Minimum)); # Eric M. Schmidt, Feb 18 2013
  • Maple
    seq(min(map(op,[entries(combinat:-character(n))])),n=1..23); # Robert Israel, Mar 31 2016
  • Mathematica
    a[n_] := With[{S = "S" <> ToString[n]}, FiniteGroupData[S, "CharacterTable"] // Flatten // Min]; Array[a, 10] (* Jean-François Alcover, Mar 31 2016 *)

Extensions

Corrected and extended by Vladeta Jovovic, May 20 2003
More terms from Eric M. Schmidt, Feb 18 2013
Showing 1-7 of 7 results.