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 A269334 #5 Aug 12 2016 07:04:23 %S A269334 1,6,74,1880,80316,5141864,458608016,54247835568,8210406468580, %T A269334 1546786612196152,354873066291138768 %N A269334 Number of nX2 arrays containing 2 copies of 0..n-1 avoiding the pattern equal-up in every row and column. %C A269334 Column 2 of A269336. %e A269334 Some solutions for n=5 %e A269334 ..3..2. .0..1. .3..1. .3..1. .3..1. .1..3. .2..3. .1..0. .2..3. .2..0 %e A269334 ..1..0. .4..2. .4..0. .4..2. .2..0. .4..4. .1..4. .3..4. .4..4. .4..3 %e A269334 ..2..3. .2..0. .4..1. .1..0. .3..4. .1..2. .0..0. .1..0. .0..1. .2..3 %e A269334 ..0..4. .3..3. .3..2. .3..4. .0..1. .3..2. .2..3. .2..3. .1..2. .0..1 %e A269334 ..4..1. .4..1. .2..0. .2..0. .2..4. .0..0. .1..4. .2..4. .0..3. .1..4 %Y A269334 Cf. A269336. %K A269334 nonn %O A269334 1,2 %A A269334 _R. H. Hardin_, Feb 24 2016