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 A278187 #3 Nov 14 2016 22:31:04 %S A278187 0,6381,6715738,6196345742,5858713218010,5537142857552112, %T A278187 5232919178331757631,4945638025497366239942,4674127103296221122266834, %U A278187 4417520697715221210576165981 %N A278187 Number of nX6 0..3 arrays with every element plus 1 mod 4 equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero. %C A278187 Column 6 of A278188. %e A278187 Some solutions for n=2 %e A278187 ..0..2..3..0..2..1. .0..1..2..3..3..1. .0..3..2..1..3..2. .0..1..0..3..0..3 %e A278187 ..1..1..3..1..3..2. .3..3..1..0..0..2. .1..2..1..2..0..1. .3..2..1..2..1..2 %Y A278187 Cf. A278188. %K A278187 nonn %O A278187 1,2 %A A278187 _R. H. Hardin_, Nov 14 2016