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 A318539 #7 Apr 20 2020 19:38:33 %S A318539 1,1,6,31,247,2905,46165,1143583,41368803,2165406865,168220637918, %T A318539 19176703676628,3204799103321623,788247777299643666, %U A318539 284810105663632654341,151134158955831615046217 %N A318539 Number of n X n 0..1 arrays with every element unequal to 0, 1, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. %C A318539 Diagonal of A318545. %H A318539 R. H. Hardin, <a href="/A318539/b318539.txt">Table of n, a(n) for n = 1..21</a> %e A318539 Some solutions for n=5 %e A318539 ..0..0..0..0..0. .0..0..0..1..0. .0..0..0..0..0. .0..0..0..0..0 %e A318539 ..0..0..0..0..0. .1..0..0..0..0. .0..0..1..0..0. .0..0..0..1..0 %e A318539 ..0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .1..0..0..0..0 %e A318539 ..0..1..0..0..1. .0..1..0..0..0. .0..0..0..0..0. .0..0..0..0..1 %e A318539 ..0..0..0..0..0. .0..0..0..1..0. .0..0..0..1..0. .0..0..0..0..0 %Y A318539 Cf. A318545. %K A318539 nonn %O A318539 1,3 %A A318539 _R. H. Hardin_, Aug 28 2018