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 A300644 #4 Mar 10 2018 10:39:08 %S A300644 0,19,104,1789,28089,456649,7455411,121708555,1990954802,32547397369, %T A300644 532327808168,8705226732028,142365129531729,2328217142648763, %U A300644 38075317550124085,622678903591246459,10183203860874999028 %N A300644 Number of nX6 0..1 arrays with every element equal to 2, 3, 4 or 5 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. %C A300644 Column 6 of A300646. %H A300644 R. H. Hardin, <a href="/A300644/b300644.txt">Table of n, a(n) for n = 1..210</a> %e A300644 Some solutions for n=5 %e A300644 ..0..0..1..1..1..1. .0..0..1..0..0..1. .0..0..1..0..0..1. .0..0..0..0..0..0 %e A300644 ..0..1..1..0..1..1. .0..1..1..0..1..1. .0..1..1..0..1..1. .0..0..0..0..0..0 %e A300644 ..0..0..0..0..0..1. .1..1..0..0..1..0. .0..0..1..0..1..0. .0..1..1..0..1..0 %e A300644 ..0..1..1..0..0..1. .0..0..1..1..0..0. .0..1..1..0..0..0. .0..1..0..1..1..0 %e A300644 ..1..1..0..0..1..1. .0..1..1..0..0..0. .0..0..0..0..0..0. .0..0..0..1..0..0 %Y A300644 Cf. A300646. %K A300644 nonn %O A300644 1,2 %A A300644 _R. H. Hardin_, Mar 10 2018