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 A203560 #7 Jul 22 2025 17:20:35 %S A203560 3,33,177,5673,32613,513903,7343451,185804265,1849858773,30348858003, %T A203560 499616140191,10882786433775,141444270208647,2412815237573445, %U A203560 41425627536496497,824284992576210537,12447291755448613317 %N A203560 Number of nX4 0..2 arrays with row sums equal and column sums equal. %C A203560 Column 4 of A203564 %H A203560 R. H. Hardin, <a href="/A203560/b203560.txt">Table of n, a(n) for n = 1..39</a> %e A203560 Some solutions for n=5 %e A203560 ..1..0..2..1....0..1..2..1....1..1..1..1....2..1..1..0....2..0..0..2 %e A203560 ..0..2..0..2....0..0..2..2....0..0..2..2....1..0..1..2....2..0..2..0 %e A203560 ..0..2..2..0....1..0..1..2....1..2..1..0....2..1..0..1....1..1..1..1 %e A203560 ..2..1..1..0....2..2..0..0....1..2..0..1....0..1..1..2....0..2..0..2 %e A203560 ..2..0..0..2....2..2..0..0....2..0..1..1....0..2..2..0....0..2..2..0 %K A203560 nonn %O A203560 1,1 %A A203560 _R. H. Hardin_ Jan 03 2012