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 A302803 #4 Apr 13 2018 13:05:22 %S A302803 4,29,169,1010,6084,36456,218640,1312416,7873344,47237760,283440384, %T A302803 1700614656,10203632640,61222127616,367332102144,2203991285760, %U A302803 13223955677184,79343718137856,476062276976640,2856373852962816 %N A302803 Number of nX3 0..1 arrays with every element equal to 0, 1, 2, 3 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302803 Column 3 of A302808. %H A302803 R. H. Hardin, <a href="/A302803/b302803.txt">Table of n, a(n) for n = 1..210</a> %F A302803 Empirical: a(n) = 6*a(n-1) +24*a(n-3) -144*a(n-4) for n>6 %e A302803 Some solutions for n=5 %e A302803 ..0..0..0. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .0..0..1. .0..1..1 %e A302803 ..1..1..0. .1..1..0. .1..0..0. .0..0..1. .1..1..0. .1..1..1. .1..0..1 %e A302803 ..1..0..1. .0..0..0. .1..1..1. .1..0..1. .0..0..0. .1..0..1. .0..1..1 %e A302803 ..0..0..1. .0..0..0. .1..1..1. .1..0..1. .1..0..1. .0..0..1. .0..1..0 %e A302803 ..0..1..1. .0..0..1. .0..0..1. .1..0..0. .0..1..1. .1..1..1. .0..0..1 %Y A302803 Cf. A302808. %K A302803 nonn %O A302803 1,1 %A A302803 _R. H. Hardin_, Apr 13 2018