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 A303406 #4 Apr 23 2018 10:39:06 %S A303406 1,7,28,119,541,2327,10384,47491,208616,938105,4229023,18855226, %T A303406 84609455,379973132,1700940358,7627893865,34215621269,153337948168, %U A303406 687522535009,3082887354405,13820286385598,61963243406462,277818915171978 %N A303406 Number of nX3 0..1 arrays with every element equal to 1, 2, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303406 Column 3 of A303410. %H A303406 R. H. Hardin, <a href="/A303406/b303406.txt">Table of n, a(n) for n = 1..210</a> %F A303406 Empirical: a(n) = 2*a(n-1) +7*a(n-2) +35*a(n-3) -36*a(n-4) -151*a(n-5) -97*a(n-6) +34*a(n-7) +258*a(n-8) -724*a(n-9) +256*a(n-10) +1584*a(n-11) -240*a(n-12) -512*a(n-13) -304*a(n-14) +1728*a(n-15) -1344*a(n-16) -1792*a(n-17) +1024*a(n-18) %e A303406 Some solutions for n=5 %e A303406 ..0..1..1. .0..1..0. .0..1..0. .0..0..0. .0..1..0. .0..0..1. .0..0..0 %e A303406 ..1..0..0. .0..0..1. .1..0..1. .0..1..0. .0..0..1. .0..1..1. .1..0..1 %e A303406 ..1..0..1. .0..0..0. .0..1..0. .1..0..0. .1..0..0. .0..1..0. .0..1..0 %e A303406 ..1..1..1. .1..1..0. .1..0..1. .1..1..0. .1..1..1. .0..0..0. .1..0..1 %e A303406 ..0..0..0. .0..0..1. .1..1..1. .1..0..1. .0..0..1. .0..0..0. .0..0..0 %Y A303406 Cf. A303410. %K A303406 nonn %O A303406 1,2 %A A303406 _R. H. Hardin_, Apr 23 2018