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 A264873 #4 Nov 27 2015 07:30:13 %S A264873 1,0,5,12,3613,207424,68488297,47123513432,79332328368931 %N A264873 Number of (n+1)X(n+1) arrays of permutations of 0..(n+1)^2-1 with each element having directed index change 0,1 0,-1 -2,0 or 1,1. %C A264873 Diagonal of A264878. %e A264873 Some solutions for n=4 %e A264873 ..1..2.12..4.14...10..2..3..4.14....1..2.12..4.14....1..2..3..4.14 %e A264873 .15..0..8..9..3....6..0..1..9.19....6..0..8..9..3....6..0.17..9.19 %e A264873 .20..5..6..7.24...20..5.22..7..8...20..5.22..7.24...20..5.22..7..8 %e A264873 .16.10.11.19.13...16.17.11.12.13...16.10.11.19.13...16.10.11.12.13 %e A264873 .21.22.23.17.18...21.15.23.24.18...21.15.23.17.18...21.15.23.24.18 %Y A264873 Cf. A264878. %K A264873 nonn %O A264873 1,3 %A A264873 _R. H. Hardin_, Nov 27 2015