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 A302310 #4 Apr 05 2018 09:39:22 %S A302310 2,3,11,21,31,113,363,813,1751,5001,14051,34053,82063,218273,579291, %T A302310 1452381,3638471,9447993,24526163,62318133,158325631,407598161, %U A302310 1049289291,2679681933,6843284663,17562012393,45069368771,115317418341 %N A302310 Number of 2Xn 0..1 arrays with every element equal to 0, 1, 3 or 4 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302310 Row 2 of A302309. %H A302310 R. H. Hardin, <a href="/A302310/b302310.txt">Table of n, a(n) for n = 1..210</a> %F A302310 Empirical: a(n) = 2*a(n-1) -a(n-2) +4*a(n-3) +12*a(n-4) -16*a(n-5) for n>6 %e A302310 Some solutions for n=5 %e A302310 ..0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..1. .0..1..0..1..0 %e A302310 ..0..0..1..0..1. .1..0..0..1..0. .0..1..0..0..0. .0..1..1..1..0 %Y A302310 Cf. A302309. %K A302310 nonn %O A302310 1,1 %A A302310 _R. H. Hardin_, Apr 05 2018