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 A203489 #6 Jul 22 2025 17:17:05 %S A203489 96,20596,3171708,442135180,61706303456,8496020082856, %T A203489 1172134178554204,161068791865426940 %N A203489 Number of nX6 0..2 arrays with row sums equal and column sums unequal to adjacent columns. %C A203489 Column 6 of A203491 %e A203489 Some solutions for n=5 %e A203489 ..2..2..2..0..1..2....2..2..0..2..2..2....1..0..0..0..1..2....1..1..1..1..1..0 %e A203489 ..0..1..2..2..2..2....2..1..1..2..2..2....1..0..2..1..0..0....1..2..1..0..0..1 %e A203489 ..0..2..1..2..2..2....2..1..1..2..2..2....2..1..0..0..0..1....1..0..2..0..1..1 %e A203489 ..1..2..0..2..2..2....0..2..2..2..2..2....2..1..0..1..0..0....0..1..0..0..2..2 %e A203489 ..1..2..2..2..0..2....1..2..2..2..1..2....1..0..1..2..0..0....1..2..0..0..2..0 %K A203489 nonn %O A203489 1,1 %A A203489 _R. H. Hardin_ Jan 02 2012