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 A203561 #7 Jul 22 2025 17:20:42 %S A203561 3,53,993,32613,2577513,39612503,1509893003,59794281893,2435292751413, %T A203561 165459828692703,4307041366439903,185658731463324903, %U A203561 8107975032968711943,358060848206529563813,21242986806159652173693,717973394997481520889893 %N A203561 Number of nX5 0..2 arrays with row sums equal and column sums equal. %C A203561 Column 5 of A203564 %H A203561 R. H. Hardin, <a href="/A203561/b203561.txt">Table of n, a(n) for n = 1..19</a> %e A203561 Some solutions for n=5 %e A203561 ..1..2..2..0..0....1..0..1..1..1....2..2..0..2..1....1..1..2..2..2 %e A203561 ..0..0..2..2..1....2..0..0..2..0....0..2..1..2..2....1..2..1..2..2 %e A203561 ..1..0..0..2..2....0..2..1..0..1....1..2..2..2..0....2..1..2..1..2 %e A203561 ..1..1..0..1..2....0..2..2..0..0....2..0..2..1..2....2..2..1..2..1 %e A203561 ..2..2..1..0..0....1..0..0..1..2....2..1..2..0..2....2..2..2..1..1 %K A203561 nonn %O A203561 1,1 %A A203561 _R. H. Hardin_ Jan 03 2012