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 A269478 #6 Apr 05 2023 08:26:56 %S A269478 1,14,574,36028,3572724,548242672,121353398100 %N A269478 Number of n X 3 arrays containing 3 copies of 0..n-1 avoiding the pattern down-up in every row and equal-up in every column. %C A269478 Column 3 of A269479. %e A269478 Some solutions for n=4 %e A269478 ..0..1..3. .0..1..0. .2..1..1. .0..1..2. .2..1..0. .1..0..2. .0..1..2 %e A269478 ..1..3..3. .1..2..2. .0..1..2. .0..3..3. .3..1..0. .1..3..2. .1..2..3 %e A269478 ..2..2..1. .2..3..3. .0..2..3. .2..3..1. .3..2..1. .3..2..3. .3..0..2 %e A269478 ..0..2..0. .3..1..0. .0..3..3. .2..1..0. .3..2..0. .0..1..0. .3..0..1 %Y A269478 Cf. A269479. %K A269478 nonn %O A269478 1,2 %A A269478 _R. H. Hardin_, Feb 27 2016