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 A264066 #9 Mar 26 2025 18:44:20 %S A264066 2,21,1210,239580,242621698,1084282319384,23180312098708413, %T A264066 2169349966829797899136 %N A264066 Number of (n+1) X (n+1) arrays of permutations of 0..(n+1)^2-1 with each element having index change +-(.,.) 0,0 1,1 or 1,2. %e A264066 Some solutions for n=3: %e A264066 ..6..1..7..3....5..1..7..3....6..1..7..3....0..1..2..3....0..6..2..3 %e A264066 .10.11..0..2....9.11..0..2....4..5..0..2...10..5..6..7....4.11..1..7 %e A264066 ..8..9..4..5....8.15..4..6...14.15.10.11...13..4.15.11....8.14.15..5 %e A264066 .12.13.14.15...12.13.14.10...12.13..8..9...12..8.14..9...12.13..9.10 %Y A264066 Main diagonal of A264071. %K A264066 nonn %O A264066 1,1 %A A264066 _R. H. Hardin_, Nov 02 2015