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 A302165 #4 Apr 02 2018 14:50:47 %S A302165 4,6,7,12,20,34,56,94,156,262,436,730,1216,2034,3392,5670,9460,15806, %T A302165 26380,44066,73560,122858,205112,342542,571916,955062,1594660,2662890, %U A302165 4446320,7424674,12397424,20701558,34566948,57720430,96380668,160937266 %N A302165 Number of 3Xn 0..1 arrays with every element equal to 0, 1 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302165 Row 3 of A302163. %H A302165 R. H. Hardin, <a href="/A302165/b302165.txt">Table of n, a(n) for n = 1..210</a> %F A302165 Empirical: a(n) = a(n-1) +a(n-2) -a(n-3) +2*a(n-4) for n>6 %e A302165 Some solutions for n=5 %e A302165 ..0..0..1..0..1. .0..0..1..1..0. .0..1..0..1..0. .0..1..0..1..0 %e A302165 ..0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..1. .1..1..0..1..1 %e A302165 ..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0 %Y A302165 Cf. A302163. %K A302165 nonn %O A302165 1,1 %A A302165 _R. H. Hardin_, Apr 02 2018