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 A203563 #6 Jul 22 2025 17:20:49 %S A203563 3,395,35619,7343451,1509893003,360255871643 %N A203563 Number of nX7 0..2 arrays with row sums equal and column sums equal. %C A203563 Column 7 of A203564 %e A203563 Some solutions for n=4 %e A203563 ..0..1..2..0..1..1..2....0..2..1..1..1..0..2....0..2..0..1..2..0..2 %e A203563 ..2..1..0..1..1..2..0....0..0..0..1..2..2..2....1..0..0..2..2..1..1 %e A203563 ..0..1..2..2..1..0..1....2..1..2..1..0..1..0....1..2..2..1..0..1..0 %e A203563 ..2..1..0..1..1..1..1....2..1..1..1..1..1..0....2..0..2..0..0..2..1 %K A203563 nonn %O A203563 1,1 %A A203563 _R. H. Hardin_ Jan 03 2012