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 A264699 #3 Nov 21 2015 07:48:53 %S A264699 1,2,5,28,159,1383,16818,168974,2921624,43918848,1166660928, %T A264699 31828563776,1193792259072,43520679101184,1622694957527040 %N A264699 Number of 2Xn arrays of permutations of 0..n*2-1 with rows nondecreasing modulo 4 and columns nondecreasing modulo 5. %C A264699 Row 2 of A264698. %e A264699 Some solutions for n=6 %e A264699 ..0..5..6..2.10.11....0..9..5..1..2..6....0..5.10..6..7.11....8..0..1.10..6..2 %e A264699 ..4..8..1..9..7..3....8..4.10.11..7..3....8..4..9..1..2..3....4..5..9.11..7..3 %Y A264699 Cf. A264698. %K A264699 nonn %O A264699 1,2 %A A264699 _R. H. Hardin_, Nov 21 2015