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 A302640 #4 Apr 10 2018 19:36:10 %S A302640 64,86,189,657,2303,8981,30216,112431,408512,1512824,5441957,20021696, %T A302640 73157743,268090840,977883198,3582780118,13103336584,47949599697, %U A302640 175342870194,641714970276,2347546538523,8589020632731,31421666502319 %N A302640 Number of 7Xn 0..1 arrays with every element equal to 0, 1, 3 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302640 Row 7 of A302635. %H A302640 R. H. Hardin, <a href="/A302640/b302640.txt">Table of n, a(n) for n = 1..210</a> %e A302640 Some solutions for n=5 %e A302640 ..0..1..1..0..1. .0..1..0..1..0. .0..0..1..0..1. .0..1..1..0..1 %e A302640 ..1..0..1..0..0. .0..0..0..1..1. .0..1..0..0..1. .1..0..1..0..1 %e A302640 ..1..0..1..0..1. .0..1..0..1..0. .0..1..0..1..0. .1..0..1..0..1 %e A302640 ..0..0..1..0..1. .0..1..0..1..0. .1..1..0..1..0. .0..0..1..0..1 %e A302640 ..0..0..0..0..1. .1..1..0..0..0. .0..1..0..1..0. .1..0..1..0..1 %e A302640 ..1..0..1..0..1. .0..1..0..1..0. .0..1..0..1..0. .1..1..1..0..0 %e A302640 ..0..1..1..0..1. .0..1..0..1..0. .0..0..1..1..0. .1..0..1..0..1 %Y A302640 Cf. A302635. %K A302640 nonn %O A302640 1,1 %A A302640 _R. H. Hardin_, Apr 10 2018