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 A300643 #4 Mar 10 2018 10:38:24 %S A300643 0,9,30,316,2998,28089,268615,2552014,24338903,231985285,2211326264, %T A300643 21081277233,200957956858,1915723519711,18262175095417, %U A300643 174090604742721,1659575837493437,15820464143773812,150813856777262673 %N A300643 Number of nX5 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 A300643 Column 5 of A300646. %H A300643 R. H. Hardin, <a href="/A300643/b300643.txt">Table of n, a(n) for n = 1..210</a> %e A300643 Some solutions for n=5 %e A300643 ..0..0..1..1..0. .0..0..0..1..1. .0..0..0..0..0. .0..0..0..1..1 %e A300643 ..0..0..1..0..0. .0..0..1..1..1. .0..0..0..0..1. .0..0..1..0..1 %e A300643 ..1..1..1..0..1. .1..1..0..0..1. .1..1..1..1..1. .1..1..0..0..1 %e A300643 ..1..0..0..1..1. .1..0..0..0..1. .1..0..0..1..0. .1..1..0..1..1 %e A300643 ..0..0..1..1..1. .1..1..1..1..1. .0..0..0..0..0. .1..1..1..1..1 %Y A300643 Cf. A300646. %K A300643 nonn %O A300643 1,2 %A A300643 _R. H. Hardin_, Mar 10 2018