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 A301966 #4 Mar 29 2018 13:03:31 %S A301966 8,34,40,64,111,219,443,904,1860,3856,8015,16659,34647,72088,150004, %T A301966 312144,649555,1351723,2812951,5853784,12181816,25350576,52755019, %U A301966 109784179,228462939,475435704,989390720,2058940864,4284695031 %N A301966 Number of 4Xn 0..1 arrays with every element equal to 0, 1 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero. %C A301966 Row 4 of A301964. %H A301966 R. H. Hardin, <a href="/A301966/b301966.txt">Table of n, a(n) for n = 1..210</a> %F A301966 Empirical: a(n) = 2*a(n-1) +a(n-3) -a(n-4) -2*a(n-6) +a(n-7) for n>9 %e A301966 Some solutions for n=5 %e A301966 ..0..0..1..0..1. .0..1..0..1..0. .0..0..1..0..1. .0..1..0..1..0 %e A301966 ..1..0..0..0..1. .0..1..0..1..0. .1..0..0..0..1. .0..1..0..0..0 %e A301966 ..1..0..1..1..1. .0..1..0..1..0. .1..0..1..1..1. .0..1..0..1..0 %e A301966 ..1..0..1..0..0. .1..0..1..0..1. .1..0..1..0..1. .0..1..0..1..0 %Y A301966 Cf. A301964. %K A301966 nonn %O A301966 1,1 %A A301966 _R. H. Hardin_, Mar 29 2018