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 A301538 #6 Jan 02 2022 17:27:49 %S A301538 8,21,61,212,658,2417,9037,33526,125626,477972,1824213,6971325, %T A301538 26702279,102479158,393541270,1511848952,5810405859,22336911663, %U A301538 85879249631,330208289450,1269748921864,4882763327280,18776842367003,72208138689837 %N A301538 Number of n X 5 0..1 arrays with every element equal to 0, 1 or 3 horizontally or vertically adjacent elements, with upper left element zero. %C A301538 Column 5 of A301541. %H A301538 R. H. Hardin, <a href="/A301538/b301538.txt">Table of n, a(n) for n = 1..210</a> %e A301538 Some solutions for n=5 %e A301538 ..0..0..1..0..1. .0..0..1..1..1. .0..1..1..1..0. .0..1..0..1..0 %e A301538 ..1..1..0..1..0. .1..1..0..1..0. .1..0..1..0..1. .1..0..1..0..1 %e A301538 ..0..0..1..0..1. .0..0..0..0..1. .0..1..0..1..1. .0..1..0..1..0 %e A301538 ..1..1..0..1..0. .1..0..1..1..0. .1..0..1..0..1. .0..0..1..0..1 %e A301538 ..0..0..1..0..1. .0..1..0..0..1. .0..1..0..0..0. .0..1..0..0..0 %Y A301538 Cf. A301541. %K A301538 nonn %O A301538 1,1 %A A301538 _R. H. Hardin_, Mar 23 2018