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 A269069 #7 Apr 19 2020 23:46:51 %S A269069 2,11,123,3288,165607,18220241,4064720816,1833956006577, %T A269069 1778703508587227,3374673365461249568,14101540722268888633757, %U A269069 114651904507399541002097761,2060026489521744559823250922304,72580676762280474254836112626897875 %N A269069 Number of n X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. %C A269069 Diagonal of A269075. %H A269069 R. H. Hardin, <a href="/A269069/b269069.txt">Table of n, a(n) for n = 1..23</a> %e A269069 Some solutions for n=4 %e A269069 ..0..0..0..1. .0..0..1..0. .0..0..0..0. .0..0..1..0. .0..0..0..1 %e A269069 ..0..0..0..1. .1..0..0..1. .1..0..0..0. .1..0..0..0. .1..0..0..1 %e A269069 ..1..0..0..0. .0..0..0..0. .0..0..0..1. .0..0..1..1. .1..0..0..0 %e A269069 ..0..1..0..0. .0..0..0..0. .0..0..0..1. .1..0..0..0. .0..0..1..0 %Y A269069 Cf. A269075. %K A269069 nonn %O A269069 1,1 %A A269069 _R. H. Hardin_, Feb 19 2016