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 A303035 #4 Apr 17 2018 13:20:13 %S A303035 3,11,14,35,71,186,459,1287,3490,9699,27707,79358,229491,669203, %T A303035 1958414,5753843,16951391,50026322,147861435,437469791,1295219194, %U A303035 3836957139,11370949011,33707274678,99940712835,296363420843,878924723910 %N A303035 Number of nX3 0..1 arrays with every element equal to 0, 1, 3, 4 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303035 Column 3 of A303040. %H A303035 R. H. Hardin, <a href="/A303035/b303035.txt">Table of n, a(n) for n = 1..210</a> %F A303035 Empirical: a(n) = 4*a(n-1) -5*a(n-2) +16*a(n-3) -36*a(n-4) +32*a(n-5) -63*a(n-6) +64*a(n-7) -51*a(n-8) +4*a(n-9) +60*a(n-10) +16*a(n-11) +112*a(n-12) +64*a(n-13) for n>16 %e A303035 Some solutions for n=5 %e A303035 ..0..1..0. .0..1..0. .0..1..0. .0..0..0. .0..1..0. .0..1..1. .0..0..0 %e A303035 ..0..1..0. .0..1..1. .0..0..0. .0..1..0. .0..0..0. .1..0..1. .0..1..0 %e A303035 ..0..1..0. .1..1..1. .0..1..0. .0..1..0. .0..1..0. .0..0..0. .0..1..1 %e A303035 ..0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..0..1. .0..1..0 %e A303035 ..0..0..0. .0..0..1. .1..0..0. .1..0..0. .0..1..0. .1..0..1. .0..0..0 %Y A303035 Cf. A303040. %K A303035 nonn %O A303035 1,1 %A A303035 _R. H. Hardin_, Apr 17 2018