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 A303249 #4 Apr 20 2018 11:06:15 %S A303249 1,14,49,250,1183,5918,28680,141255,691968,3391358,16627204,81517689, %T A303249 399591042,1958997017,9603668921,47080079771,230803211309, %U A303249 1131476255863,5546875012244,27192677194545,133307748424215,653519804327678 %N A303249 Number of nX3 0..1 arrays with every element equal to 1, 2, 3, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303249 Column 3 of A303254. %H A303249 R. H. Hardin, <a href="/A303249/b303249.txt">Table of n, a(n) for n = 1..210</a> %F A303249 Empirical: a(n) = 4*a(n-1) +6*a(n-2) +7*a(n-3) -61*a(n-4) -78*a(n-5) +115*a(n-6) +26*a(n-7) -126*a(n-8) -300*a(n-9) +380*a(n-10) -80*a(n-11) +144*a(n-12) -32*a(n-13) +128*a(n-14) %e A303249 Some solutions for n=5 %e A303249 ..0..1..1. .0..0..0. .0..1..1. .0..1..0. .0..0..1. .0..0..1. .0..0..1 %e A303249 ..1..0..1. .1..1..0. .1..0..1. .1..0..1. .0..1..1. .1..1..1. .0..1..0 %e A303249 ..1..1..1. .0..1..1. .0..1..0. .1..1..1. .0..1..1. .0..0..0. .1..0..1 %e A303249 ..0..0..1. .1..0..0. .1..0..0. .1..1..1. .0..0..1. .1..1..0. .1..1..0 %e A303249 ..1..1..0. .0..1..1. .1..1..1. .1..0..0. .1..1..0. .1..0..1. .1..0..1 %Y A303249 Cf. A303254. %K A303249 nonn %O A303249 1,2 %A A303249 _R. H. Hardin_, Apr 20 2018