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 A269005 #7 Apr 19 2020 23:45:45 %S A269005 0,4,46,2136,109058,14382480,3258530608,1582785864320, %T A269005 1554970236400402,3055129067325800608,12891237725516640144940, %U A269005 106775629834644247372248448,1932363567303596958505554161216,68821810412730939070416537380998580 %N A269005 Number of n X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once. %C A269005 Diagonal of A269011. %H A269005 R. H. Hardin, <a href="/A269005/b269005.txt">Table of n, a(n) for n = 1..23</a> %e A269005 Some solutions for n=4 %e A269005 ..0..0..0..0. .1..0..0..0. .1..0..0..1. .0..0..1..0. .1..0..0..0 %e A269005 ..1..0..1..0. .0..0..0..1. .1..0..0..0. .1..0..1..0. .0..0..0..0 %e A269005 ..0..0..0..0. .1..1..0..0. .1..0..0..1. .0..0..0..0. .1..0..0..0 %e A269005 ..1..0..1..1. .0..0..0..1. .0..0..1..0. .0..1..1..0. .0..0..1..1 %Y A269005 Cf. A269011. %K A269005 nonn %O A269005 1,2 %A A269005 _R. H. Hardin_, Feb 17 2016