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 A303680 #4 Apr 28 2018 09:22:03 %S A303680 13,49,39,64,110,177,245,335,467,657,949,1391,2035,2937,4221,6079, %T A303680 8771,12657,18269,26383,38091,54969,79317,114471,165219,238457,344157, %U A303680 496719,716907,1034681,1493309,2155247,3110611,4489449,6479477,9351631,13496923 %N A303680 Number of nX6 0..1 arrays with every element unequal to 0, 1 or 3 king-move adjacent elements, with upper left element zero. %C A303680 Column 6 of A303682. %H A303680 R. H. Hardin, <a href="/A303680/b303680.txt">Table of n, a(n) for n = 1..210</a> %F A303680 Empirical: a(n) = a(n-1) +a(n-4) +a(n-7) for n>12 %e A303680 Some solutions for n=5 %e A303680 ..0..1..1..1..1..0. .0..0..0..0..0..0. .0..0..0..0..0..0. .0..1..1..0..0..0 %e A303680 ..1..1..1..1..1..1. .1..0..0..0..0..0. .0..0..0..0..0..0. .1..1..1..1..0..0 %e A303680 ..1..1..1..1..1..1. .1..1..0..0..0..0. .0..0..0..0..0..0. .1..1..1..1..1..0 %e A303680 ..1..1..1..1..1..1. .1..1..1..0..0..0. .0..0..0..0..0..0. .1..1..1..1..1..1 %e A303680 ..1..1..1..1..1..0. .1..1..1..1..0..0. .0..0..0..0..0..1. .1..1..1..1..1..1 %Y A303680 Cf. A303682. %K A303680 nonn %O A303680 1,1 %A A303680 _R. H. Hardin_, Apr 28 2018