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 A186166 #6 Apr 26 2021 21:13:31 %S A186166 40,99933,87054174,95752776009,96951738076992,101554003879403823 %N A186166 1/4 the number of n X 7 0..3 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors. %C A186166 Column 7 of A186168. %e A186166 Some solutions for 4 X 7 with a(1,1) = 0 %e A186166 ..0..0..2..0..0..0..1....0..0..2..0..0..3..0....0..0..2..0..0..0..0 %e A186166 ..0..0..2..0..2..2..1....0..0..2..0..3..3..0....0..0..2..0..2..2..1 %e A186166 ..2..2..0..2..3..3..1....2..2..0..2..3..0..1....2..2..0..1..2..1..1 %e A186166 ..0..0..0..2..3..2..2....0..0..0..2..0..0..1....0..0..0..1..1..3..3 %Y A186166 Cf. A186168. %K A186166 nonn %O A186166 1,1 %A A186166 _R. H. Hardin_ Feb 13 2011