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 A289645 #6 Apr 05 2020 23:31:41 %S A289645 0,2,11,44,170,642,2421,9142,34572,131086,498465,1900928,7269978, %T A289645 27879108,107183763,413052074,1595247760,6173412924,23934713193, %U A289645 92955294982,361580812792,1408539219596,5494347736318,21458645441596 %N A289645 Number of n X 2 0..1 arrays with the number of 1's horizontally, antidiagonally or vertically adjacent to some 0 two less than the number of 0's adjacent to some 1. %C A289645 Column 2 of A289651. %H A289645 R. H. Hardin, <a href="/A289645/b289645.txt">Table of n, a(n) for n = 1..210</a> %e A289645 Some solutions for n=4 %e A289645 ..0..1. .0..1. .0..0. .1..0. .0..0. .0..0. .0..1. .1..0. .0..1. .0..1 %e A289645 ..0..1. .0..1. .1..0. .1..0. .1..1. .1..0. .0..1. .0..0. .1..0. .1..0 %e A289645 ..0..0. .0..0. .1..0. .0..1. .0..0. .0..1. .0..1. .1..0. .0..0. .0..1 %e A289645 ..0..0. .0..1. .0..1. .0..0. .1..0. .1..0. .0..0. .0..1. .0..1. .0..0 %Y A289645 Cf. A289651. %K A289645 nonn %O A289645 1,2 %A A289645 _R. H. Hardin_, Jul 09 2017