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 A269645 #5 Aug 12 2016 07:05:19 %S A269645 1,14,574,68876,18375702,9213264418,7725775442284 %N A269645 Number of nX3 arrays containing 3 copies of 0..n-1 avoiding the pattern down-up in every row and equal-up in every column. %C A269645 Column 3 of A269646. %e A269645 Some solutions for n=4 %e A269645 ..0..0..3. .2..3..1. .0..2..2. .1..3..0. .3..3..0. .2..3..1. .3..0..0 %e A269645 ..3..2..2. .3..3..0. .2..3..1. .2..2..1. .0..0..2. .3..2..0. .1..3..1 %e A269645 ..3..2..0. .1..2..2. .0..1..3. .3..3..2. .1..2..3. .0..0..3. .2..2..2 %e A269645 ..1..1..1. .0..1..0. .0..1..3. .0..0..1. .1..2..1. .2..1..1. .3..1..0 %Y A269645 Cf. A269646. %K A269645 nonn %O A269645 1,2 %A A269645 _R. H. Hardin_, Mar 02 2016