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 A303258 #4 Apr 20 2018 11:12:27 %S A303258 0,1172,28680,349273,11394429,306224454,7600681910,204093228252, %T A303258 5314350209386,138643667659572,3640560048826152,95207607193735652, %U A303258 2491557031345822081,65239890207048823769,1707524253811111768156 %N A303258 Number of 7Xn 0..1 arrays with every element equal to 1, 2, 3, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303258 Row 7 of A303254. %H A303258 R. H. Hardin, <a href="/A303258/b303258.txt">Table of n, a(n) for n = 1..210</a> %e A303258 Some solutions for n=5 %e A303258 ..0..0..0..0..0. .0..0..0..1..0. .0..0..0..1..0. .0..0..0..1..0 %e A303258 ..0..0..1..1..0. .0..0..1..0..1. .0..0..1..0..1. .0..0..1..0..0 %e A303258 ..1..0..1..0..1. .1..0..1..0..1. .1..0..1..1..1. .0..1..0..0..0 %e A303258 ..0..1..1..1..0. .0..1..1..1..0. .1..1..1..0..1. .1..1..0..1..0 %e A303258 ..0..1..0..0..0. .0..0..0..1..0. .1..0..0..0..0. .1..0..1..0..1 %e A303258 ..0..0..0..1..0. .0..1..0..0..1. .1..1..0..1..1. .1..1..1..0..0 %e A303258 ..1..1..0..1..1. .1..1..0..1..0. .0..0..0..1..1. .1..0..0..1..1 %Y A303258 Cf. A303254. %K A303258 nonn %O A303258 1,2 %A A303258 _R. H. Hardin_, Apr 20 2018