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 A264561 #3 Nov 17 2015 18:05:45 %S A264561 1,3,24,316,6080,149824,5728896,259780608,14154310656,1054215834624 %N A264561 Number of 2Xn arrays of permutations of 0..n*2-1 with rows nondecreasing modulo 2 and columns nondecreasing modulo 3. %C A264561 Row 2 of A264560. %e A264561 Some solutions for n=4 %e A264561 ..0..2..4..3....6..5..1..3....6..0..7..3....0..2..6..4....6..2..4..0 %e A264561 ..6..5..7..1....0..2..4..7....2..4..1..5....7..5..3..1....3..5..1..7 %Y A264561 Cf. A264560. %K A264561 nonn %O A264561 1,2 %A A264561 _R. H. Hardin_, Nov 17 2015