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 A301958 #7 Apr 20 2020 00:03:38 %S A301958 1,5,16,64,311,2544,33860,655332,20467528,1126897464,99461928147, %T A301958 13746050749383,3153776142960984,1195380968976593488, %U A301958 725993180042754573732,714087263476969685695404 %N A301958 Number of n X n 0..1 arrays with every element equal to 0, 1 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero. %C A301958 Diagonal of A301964. %H A301958 R. H. Hardin, <a href="/A301958/b301958.txt">Table of n, a(n) for n = 1..25</a> %e A301958 Some solutions for n=5 %e A301958 ..0..1..0..0..1. .0..0..1..0..1. .0..1..1..0..1. .0..1..1..0..1 %e A301958 ..0..1..1..0..1. .1..0..1..0..1. .0..0..1..0..1. .0..0..1..1..1 %e A301958 ..0..0..1..0..1. .1..1..1..0..0. .1..1..1..0..1. .1..0..1..0..1 %e A301958 ..1..0..1..1..1. .1..0..1..1..0. .1..0..1..0..0. .1..0..0..0..1 %e A301958 ..1..0..1..0..1. .1..0..0..1..1. .1..0..1..1..0. .1..0..1..0..0 %Y A301958 Cf. A301964. %K A301958 nonn %O A301958 1,2 %A A301958 _R. H. Hardin_, Mar 29 2018