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 A302511 #4 Apr 09 2018 09:06:07 %S A302511 5,5,15,28,48,89,163,297,544,1004,1848,3393,6237,11481,21122,38834, %T A302511 71418,131383,241665,444451,817450,1503590,2765570,5086571,9355603, %U A302511 17207807,31650188,58213496,107071156,196935005,362220199,666226093,1225380420 %N A302511 Number of nX4 0..1 arrays with every element equal to 0, 1, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302511 Column 4 of A302515. %H A302511 R. H. Hardin, <a href="/A302511/b302511.txt">Table of n, a(n) for n = 1..210</a> %F A302511 Empirical: a(n) = a(n-1) +2*a(n-3) +2*a(n-4) -a(n-6) -a(n-7) for n>10 %e A302511 Some solutions for n=5 %e A302511 ..0..1..0..1. .0..1..0..1. .0..0..1..0. .0..1..1..1. .0..0..0..1 %e A302511 ..0..1..0..1. .0..1..0..1. .1..1..1..0. .0..1..0..1. .0..1..0..1 %e A302511 ..0..0..1..1. .0..1..0..1. .1..0..0..0. .0..0..0..1. .0..1..1..1 %e A302511 ..0..1..0..1. .0..1..1..1. .1..0..1..0. .0..1..1..1. .0..0..0..1 %e A302511 ..0..1..0..1. .0..1..0..0. .1..1..1..0. .0..1..0..0. .0..1..0..1 %Y A302511 Cf. A302515. %K A302511 nonn %O A302511 1,1 %A A302511 _R. H. Hardin_, Apr 09 2018