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 A264817 #3 Nov 25 2015 21:46:08 %S A264817 1,8,59,743,17869,530230,16961815,1040174384 %N A264817 Number of nX3 arrays of permutations of 0..n*3-1 with rows nondecreasing modulo 3 and columns nondecreasing modulo 7. %C A264817 Column 3 of A264818. %e A264817 Some solutions for n=5 %e A264817 ..9..0.14....0.10.14....0..1..7....7..1.14....7.14..8....0.14..8....0..7.10 %e A264817 .10..7..2....7..4..1....9..3.14....0..9..8....9..0..2....1..7..4...14..8.11 %e A264817 ..3..8.11....2..5..8...12.10..8...10..5..2....3..1.10...10..2.11....1..2..5 %e A264817 .12..1..4....9.13.11....6.11..2....3..6.11....4..5.11...12..9..5....3..9.12 %e A264817 ..6.13..5....3..6.12...13..4..5...12.13..4...12..6.13....6..3.13....6..4.13 %Y A264817 Cf. A264818. %K A264817 nonn %O A264817 1,2 %A A264817 _R. H. Hardin_, Nov 25 2015