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 A303315 #4 Apr 21 2018 12:49:14 %S A303315 4,4,12,17,24,67,158,298,595,1337,2863,5840,12231,26168,55140,115193, %T A303315 242621,512713,1078852,2267487,4776110,10063518,21181387,44579665, %U A303315 93874659,197672892,416137435,876080072,1844597384,3883701257,8176491213 %N A303315 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303315 Row 3 of A303314. %H A303315 R. H. Hardin, <a href="/A303315/b303315.txt">Table of n, a(n) for n = 1..210</a> %F A303315 Empirical: a(n) = a(n-1) +3*a(n-3) +4*a(n-4) for n>7 %e A303315 Some solutions for n=5 %e A303315 ..0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..1. .0..0..0..1..0 %e A303315 ..0..1..1..1..1. .0..1..1..0..0. .0..1..0..0..0. .0..1..0..1..0 %e A303315 ..0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0 %Y A303315 Cf. A303314. %K A303315 nonn %O A303315 1,1 %A A303315 _R. H. Hardin_, Apr 21 2018