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 A301612 #4 Mar 24 2018 11:40:34 %S A301612 3,111,2131,40085,758338,14345706,271301458,5131197358,97045266159, %T A301612 1835413254015,34712996298775,656524254453280,12416789603607923, %U A301612 234837748693978527,4441467446525879000,84001117092821240904 %N A301612 Number of nX5 0..1 arrays with every element equal to 1, 2 or 3 horizontally or vertically adjacent elements, with upper left element zero. %C A301612 Column 5 of A301615. %H A301612 R. H. Hardin, <a href="/A301612/b301612.txt">Table of n, a(n) for n = 1..210</a> %H A301612 R. H. Hardin, <a href="/A301612/a301612.txt">Empirical recurrence of order 68</a> %F A301612 Empirical recurrence of order 68 (see link above) %e A301612 Some solutions for n=5 %e A301612 ..0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0 %e A301612 ..1..1..1..0..0. .0..0..1..0..1. .1..0..1..1..0. .1..1..1..1..0 %e A301612 ..1..1..1..1..0. .1..0..1..0..1. .1..1..1..0..1. .1..1..0..0..0 %e A301612 ..0..0..0..1..1. .1..0..1..1..1. .1..1..0..0..1. .0..1..1..0..0 %e A301612 ..1..1..1..1..1. .1..0..1..1..1. .1..1..0..0..1. .0..1..1..1..1 %Y A301612 Cf. A301615. %K A301612 nonn %O A301612 1,1 %A A301612 _R. H. Hardin_, Mar 24 2018