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 A269337 #6 Aug 12 2016 06:54:17 %S A269337 6,74,852,10210,124466,1539739,19271229,243392830,3095718114, %T A269337 39591108117,508549674595,6555349397662,84743875128342, %U A269337 1098136390356477,14258478535216226,185450173389172712,2415532450075364094 %N A269337 Number of 3Xn arrays containing n copies of 0..3-1 avoiding the pattern equal-up in every row and column. %C A269337 Row 3 of A269336. %H A269337 R. H. Hardin, <a href="/A269337/b269337.txt">Table of n, a(n) for n = 1..49</a> %e A269337 Some solutions for n=4 %e A269337 ..0..1..2..2. .1..2..1..2. .2..2..2..1. .1..0..2..0. .1..1..0..1 %e A269337 ..2..1..2..0. .0..2..1..1. .1..2..1..1. .0..2..1..2. .0..2..2..2 %e A269337 ..1..1..0..0. .2..0..0..0. .0..0..0..0. .1..2..0..1. .0..1..2..0 %Y A269337 Cf. A269336. %K A269337 nonn %O A269337 1,1 %A A269337 _R. H. Hardin_, Feb 24 2016