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 A058409 #10 May 10 2013 12:44:33 %S A058409 1,3,18,92,458,1982,7928,28592,95138,292993,845027,2295322,5915631, %T A058409 14535676,34224682,77510148,169459010,358698558,737106306,1473867060, %U A058409 2873564862,5472731212,10198198452,18621343624,33361303957,58713103696 %N A058409 Number of 4 X n nonnegative integer matrices with all column sums 3, up to row and column permutation. %H A058409 Vladeta Jovovic, <a href="/A058407/a058407.pdf">Number of m x l nonnegative integer matrices with all column sums equal to n, up to row and column permutation</a> %F A058409 G.f.: 1 / 24*(1 / (1 - x)^20 + 6 / (1 - x)^6 / (1 - x^2)^7 + 3 / (1 - x^2)^10 + 8 / (1 - x)^2 / (1 - x^3)^6 + 6 / (1 - x^4)^5). %Y A058409 Cf. A050532, A058390, A058407, A058408, A058410. %K A058409 easy,nonn %O A058409 0,2 %A A058409 _Vladeta Jovovic_, Nov 25 2000 %E A058409 More terms from _Max Alekseyev_, Jun 21 2011