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 A302948 #4 Apr 16 2018 11:37:47 %S A302948 1,15,86,587,3815,25131,164916,1083375,7114906,46729709,306907879, %T A302948 2015697730,13238601897,86947883732,571052268590,3750530654213, %U A302948 24632561409541,161780595565168,1062535099406293,6978468794154813 %N A302948 Number of nX3 0..1 arrays with every element equal to 1, 2, 3, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302948 Column 3 of A302953. %H A302948 R. H. Hardin, <a href="/A302948/b302948.txt">Table of n, a(n) for n = 1..210</a> %F A302948 Empirical: a(n) = 4*a(n-1) +15*a(n-2) +13*a(n-3) -2*a(n-4) -19*a(n-5) -3*a(n-6) +4*a(n-8) %e A302948 Some solutions for n=5 %e A302948 ..0..1..0. .0..1..1. .0..1..0. .0..1..1. .0..1..0. .0..1..0. .0..1..1 %e A302948 ..0..0..1. .0..0..0. .1..0..0. .0..0..0. .1..0..0. .1..0..0. .0..0..1 %e A302948 ..0..1..0. .1..0..0. .1..1..0. .0..1..0. .0..1..0. .0..0..0. .1..1..1 %e A302948 ..1..0..1. .1..1..1. .1..1..0. .0..0..1. .0..1..0. .1..1..1. .0..0..0 %e A302948 ..1..1..0. .0..0..0. .0..0..0. .0..0..0. .1..0..0. .1..1..1. .0..0..0 %Y A302948 Cf. A302953. %K A302948 nonn %O A302948 1,2 %A A302948 _R. H. Hardin_, Apr 16 2018