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 A302004 #4 Mar 30 2018 12:33:38 %S A302004 0,233,499,1394,110036,729297,15243860,204666568,2933712940, %T A302004 44201068772,631467436258,9310616032492,135219892970154, %U A302004 1977188363830961,28827781254085548,420748594948205104,6138969205830064789 %N A302004 Number of 7Xn 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero. %C A302004 Row 7 of A301999. %H A302004 R. H. Hardin, <a href="/A302004/b302004.txt">Table of n, a(n) for n = 1..210</a> %e A302004 Some solutions for n=5 %e A302004 ..0..0..1..1..0. .0..0..1..1..0. .0..0..0..0..1. .0..0..0..1..1 %e A302004 ..0..1..0..0..0. .0..0..0..0..0. .1..1..1..1..1. .1..1..1..0..0 %e A302004 ..1..1..0..1..1. .1..1..0..1..1. .0..0..1..0..0. .0..0..1..1..0 %e A302004 ..1..0..1..1..1. .1..1..0..0..1. .0..1..1..0..1. .0..0..1..0..1 %e A302004 ..0..0..1..0..0. .0..0..0..1..1. .0..0..0..1..1. .0..0..0..1..1 %e A302004 ..1..1..1..1..1. .0..1..0..1..1. .1..1..0..1..1. .1..1..0..0..0 %e A302004 ..1..0..0..0..0. .1..0..0..0..0. .1..0..0..0..0. .1..0..1..1..1 %Y A302004 Cf. A301999. %K A302004 nonn %O A302004 1,2 %A A302004 _R. H. Hardin_, Mar 30 2018