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 A301996 #4 Mar 30 2018 12:24:34 %S A301996 3,18,84,468,2856,17800,110036,674984,4130664,25284068,154853080, %T A301996 948637896,5811528980,35601208264,218086661704,1335953081860, %U A301996 8183781374680,50132301702344,307101237458324,1881245567361512 %N A301996 Number of nX5 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero. %C A301996 Column 5 of A301999. %H A301996 R. H. Hardin, <a href="/A301996/b301996.txt">Table of n, a(n) for n = 1..210</a> %F A301996 Empirical: a(n) = 18*a(n-1) -141*a(n-2) +661*a(n-3) -2058*a(n-4) +4393*a(n-5) -6412*a(n-6) +6060*a(n-7) -3280*a(n-8) +640*a(n-9) +192*a(n-10) -64*a(n-11) for n>12 %e A301996 Some solutions for n=5 %e A301996 ..0..0..0..0..0. .0..0..1..1..0. .0..0..1..1..1. .0..0..1..0..0 %e A301996 ..1..1..1..1..0. .1..1..1..0..1. .0..0..0..0..1. .0..1..0..0..0 %e A301996 ..0..0..1..0..0. .1..0..1..1..1. .1..1..1..1..0. .1..1..0..1..1 %e A301996 ..0..1..1..1..0. .0..0..1..0..1. .0..0..0..0..0. .0..0..1..0..0 %e A301996 ..0..0..1..0..0. .0..0..0..1..1. .1..1..0..1..1. .1..1..0..1..1 %Y A301996 Cf. A301999. %K A301996 nonn %O A301996 1,1 %A A301996 _R. H. Hardin_, Mar 30 2018