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.

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A380611 Irregular triangle read by rows: T(r,c) is the product of the number of standard Young tableaux (A117506) and the number of semistandard Young tableaux (A262030) for partitions of r.

Original entry on oeis.org

1, 1, 3, 1, 10, 16, 1, 35, 135, 40, 45, 1, 126, 896, 875, 756, 375, 96, 1, 462, 5250, 10206, 8400, 2450, 14336, 2800, 875, 1701, 175, 1, 1716, 28512, 90552, 74250, 65856, 257250, 48000, 74088, 55566, 102900, 8100, 10976, 5488, 288, 1, 6435, 147147, 686400, 567567, 931392, 3244032, 606375, 194040, 2910600, 1448832, 2673000, 202125, 666792, 846720, 1029000, 491520, 19845, 24696, 65856, 14400, 441, 1
Offset: 0

Views

Author

Wouter Meeussen, Jan 28 2025

Keywords

Comments

Partitions are generated in reverse lexicographic order.
Remark that A262030 uses Abramowitz-Stegun (A-St) order.
Sum of row r equals r^r for r > 0 (Robinson-Schensted correspondence).

Examples

			Triangle begins:
    1;
    1;
    3,    1;
   10,   16,     1;
   35,  135,    40,   45,    1;
  126,  896,   875,  756,  375,    96,    1;
  462, 5250, 10206, 8400, 2450, 14336, 2800, 875, 1701, 175, 1;
  ...
Fourth row is 1*35, 3*45, 2*20, 3*15, 1*1 with sum 256 = 4^4.
		

Crossrefs

Row sums give A000312.
Row lengths give A000041.
Leftmost column gives A088218.

Programs

  • Mathematica
    Needs["Combinatorica`"];
    hooklength[par_?PartitionQ]:=Table[Count[par,q_/;q>=j]+1-i+par[[i]]-j,{i,Length[par]},{j,par[[i]]}];
    countSYT[par_?PartitionQ]:=Tr[par]!/Times@@Flatten[hooklength[par]];
    content[par_?PartitionQ]:=Table[j-i,{i,Length[par]},{j,par[[i]]}];
    countSSYT[par_?PartitionQ,t_Integer_]:=Times@@((t+Flatten[content[par]])/Flatten[hooklength[par]]);
    Table[countSYT[par] countSSYT[par,n],{n,8},{par,IntegerPartitions[n]}]

A054688 Number of nonnegative integer n X n matrices with sum of elements equal to n; polynomial symmetric functions of matrix of order n.

Original entry on oeis.org

1, 1, 10, 165, 3876, 118755, 4496388, 202927725, 10639125640, 635627275767, 42634215112710, 3172596834321200, 259398433286078100, 23116565732981832150, 2230164446387219893320, 231574204669402103059965, 25751746463640423324267024, 3053419608195531383028424575
Offset: 0

Views

Author

Vladeta Jovovic, Apr 19 2000

Keywords

Comments

Conjecture: a(n) equals the sum of squares of the number of semistandard Young tableaux over all partitions of n. - Wouter Meeussen, Feb 02 2025

References

  • E. R. Cavalcanti and M. A. Spohn, On the applicability of mobility metrics for user movement pattern recognition in MANETs, in Proceeding MobiWac '13 Proceedings of the 11th ACM international symposium on Mobility management and wireless access, Pages 123-130, ACM New York, NY, USA 2013, ISBN: 978-1-4503-2355-0 doi:10.1145/2508222.2508228

Crossrefs

Programs

  • Maple
    a:= n-> binomial(n*(n+1)-1, n):
    seq(a(n), n=0..17);  # Alois P. Heinz, Oct 22 2021
  • Mathematica
    Table[Binomial[n^2 + n - 1, n], {n, 0, 17}] (* Michael De Vlieger, Oct 05 2017 *)
  • PARI
    a(n) = binomial(n^2+n-1, n); \\ Altug Alkan, Oct 03 2017

Formula

a(n) = C(n^2+n-1, n).
a(n) = [x^n] 1/(1 - x)^(n^2). - Ilya Gutkovskiy, Oct 03 2017
a(n) ~ exp(n + 1/2) * n^(n - 1/2) / sqrt(2*Pi). - Vaclav Kotesovec, Aug 06 2025

Extensions

a(15) corrected by Ilya Gutkovskiy, Oct 03 2017
Showing 1-2 of 2 results.