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 A278191 #4 Nov 14 2016 22:34:14 %S A278191 0,200,13720,1075258,81691958,6196345742,469577175712,35577034730206, %T A278191 2695338849906758,204197662339944373,15469874074262345128, %U A278191 1171986102689397728682,88788773705648773915186 %N A278191 Number of 4Xn 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 A278191 Row 4 of A278188. %H A278191 R. H. Hardin, <a href="/A278191/b278191.txt">Table of n, a(n) for n = 1..210</a> %e A278191 Some solutions for n=3 %e A278191 ..0..3..2. .0..3..2. .0..1..2. .0..2..1. .0..3..2. .0..3..1. .0..1..0 %e A278191 ..1..2..1. .1..2..3. .3..1..3. .1..3..1. .1..1..0. .1..2..2. .1..2..3 %e A278191 ..0..3..2. .2..1..0. .2..3..0. .2..0..2. .2..0..3. .3..1..1. .0..0..2 %e A278191 ..0..1..0. .3..0..0. .1..3..2. .1..2..3. .3..3..3. .0..2..0. .2..3..2 %Y A278191 Cf. A278188. %K A278191 nonn %O A278191 1,2 %A A278191 _R. H. Hardin_, Nov 14 2016