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.
%I A178718 #60 Sep 04 2025 13:06:01 %S A178718 1,3,7,21,57,182,565,1931,6670,24537,92337,364602,1477148,6219031, %T A178718 26875932,119930947,548688443,2580814003,12425175838,61302331782, %U A178718 309055818656,1592723862598,8374123173858,44917765035082,245452258746785,1366116578058731,7736098938006873,44558958700083896 %N A178718 Duplicate of A104779. %C A178718 a(n) is the number of symmetric nonnegative integer matrices with sum of entries equal to n, no zero rows or columns, and weakly decreasing row and column sums. - _Ludovic Schwob_, Aug 29 2023 %H A178718 Ludovic Schwob, <a href="/A178718/b178718.txt">Table of n, a(n) for n = 1..39</a> %H A178718 E. Egge et al., <a href="https://web.archive.org/web/20120103121601/http://www.cems.uvm.edu/~gwarring/research/kinv9.pdf">From quasisymmetric expansions to Schur expansions via a modified inverse Kostka matrix</a> %H A178718 E. Egge et al., <a href="https://doi.org/10.1016/j.ejc.2010.05.010">From quasisymmetric expansions to Schur expansions via a modified inverse Kostka matrix</a>, European Journal of Combinatorics, Volume 31, Issue 8, December 2010, Pages 2014-2027. %H A178718 Wouter Meeussen, <a href="https://web.archive.org/web/20220707134645/http://users.telenet.be/Wouter.Meeussen/ToolBox.nb">Schur Polynomials</a> %H A178718 Wouter Meeussen, <a href="/A178718/a178718.txt">Kostka numbers up to partitions of 20</a> %H A178718 Wouter Meeussen, <a href="/A178718/a178718_1.txt">Mathematica code for 'kostka' function</a> %H A178718 Ludovic Schwob, <a href="https://arxiv.org/abs/2506.04007">On the enumeration of double cosets and self-inverse double cosets</a>, arXiv:2506.04007 [math.CO], 2025. See p. 13. %e A178718 For n=4, {1,1,1,1,1} + {0,1,1,2,3} + {0,0,1,1,2} + {0,0,0,1,3} + {0,0,0,0,1} = 21. %t A178718 (* See Meeussen link. *) %Y A178718 Row sums of A104778. %K A178718 dead %O A178718 1,2 %A A178718 _Wouter Meeussen_, Dec 26 2010 %E A178718 a(21) onwards from _Ludovic Schwob_, Feb 22 2023