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 A198913 #8 Mar 12 2023 14:18:22 %S A198913 203,10856948,3352514013159,1243368053336112649, %T A198913 467181941240736711604077,175702802690666247458883923440, %U A198913 66084692925071529966599521403836686,24855655340700384655492554800723374323095,9348667576846602621032033514210811069676125541 %N A198913 Number of n X 7 0..7 arrays with values 0..7 introduced in row major order and no element equal to any horizontal or vertical neighbor. %H A198913 Andrew Howroyd, <a href="/A198913/b198913.txt">Table of n, a(n) for n = 1..150</a> %e A198913 Some solutions with values 0 to 7 for n=3 %e A198913 ..0..1..0..2..0..1..3....0..1..0..2..3..4..2....0..1..0..2..0..1..3 %e A198913 ..1..0..2..0..4..2..5....1..0..2..0..4..5..0....1..0..2..0..4..3..5 %e A198913 ..0..1..0..6..7..3..0....0..1..0..4..5..6..7....0..1..0..6..7..0..1 %Y A198913 Column 7 of A198914. %K A198913 nonn %O A198913 1,1 %A A198913 _R. H. Hardin_, Oct 31 2011 %E A198913 Terms a(8) and beyond from _Andrew Howroyd_, Mar 12 2023