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 A301785 #7 Apr 20 2020 00:01:55 %S A301785 1,5,12,32,82,205,508,1258,3129,7837,19782,50310,128803,331592,857434, %T A301785 2224726,5787130,15082283,39360630,102820286,268777679,702935723, %U A301785 1839002254,4812250428,12594535285,32965703404,86292668280,225894991484 %N A301785 Number of n X n 0..1 arrays with every element equal to 0 or 1 horizontally or antidiagonally adjacent elements, with upper left element zero. %C A301785 Diagonal of A301790. %H A301785 R. H. Hardin, <a href="/A301785/b301785.txt">Table of n, a(n) for n = 1..36</a> %e A301785 Some solutions for n=5 %e A301785 ..0..1..1..0..1. .0..1..1..0..0. .0..1..0..1..0. .0..1..1..0..1 %e A301785 ..0..0..1..0..0. .0..0..1..1..0. .0..1..0..1..0. .0..0..1..0..1 %e A301785 ..1..0..1..1..0. .1..0..0..1..1. .0..1..0..1..0. .1..0..1..0..1 %e A301785 ..1..0..0..1..1. .1..1..0..0..1. .0..1..0..1..0. .1..0..1..0..0 %e A301785 ..1..1..0..0..1. .0..1..1..0..1. .0..1..0..1..0. .1..0..1..1..0 %Y A301785 Cf. A301790. %K A301785 nonn %O A301785 1,2 %A A301785 _R. H. Hardin_, Mar 26 2018