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 A278193 #4 Nov 14 2016 22:35:42 %S A278193 0,11794,8803344,7737459027,6545874548694,5537142857552112, %T A278193 4678308031001778581,3951925612543275997042,3338154929554215989823146, %U A278193 2819671588394426773289855424,2381712111047192598048356777986 %N A278193 Number of 6Xn 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 A278193 Row 6 of A278188. %H A278193 R. H. Hardin, <a href="/A278193/b278193.txt">Table of n, a(n) for n = 1..18</a> %e A278193 Some solutions for n=2 %e A278193 ..0..3. .0..3. .0..1. .0..1. .0..1. .0..2. .0..2. .0..1. .0..1. .0..1 %e A278193 ..1..2. .1..2. .1..2. .0..2. .0..2. .1..3. .1..3. .3..2. .0..2. .0..2 %e A278193 ..2..0. .1..3. .0..3. .1..3. .2..3. .0..2. .0..0. .1..3. .2..3. .2..3 %e A278193 ..3..3. .3..0. .3..2. .0..1. .1..0. .1..3. .3..0. .2..0. .3..1. .3..1 %e A278193 ..3..2. .0..2. .3..1. .0..2. .3..1. .1..2. .2..1. .2..3. .0..2. .0..2 %e A278193 ..0..1. .1..3. .0..0. .3..3. .0..2. .3..0. .0..3. .1..0. .3..3. .2..3 %Y A278193 Cf. A278188. %K A278193 nonn %O A278193 1,2 %A A278193 _R. H. Hardin_, Nov 14 2016