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 A297502 #4 Dec 31 2017 07:25:28 %S A297502 7,68,314,2281,14201,88808,573119,3613793,22999331,146183595, %T A297502 928047561,5898371728,37468267405,238038322708,1512327060362, %U A297502 9607753234896,61039432234655,387788945511548,2463656446529920,15651856594703719 %N A297502 Number of nX4 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 or 2 neighboring 1s. %C A297502 Column 4 of A297506. %H A297502 R. H. Hardin, <a href="/A297502/b297502.txt">Table of n, a(n) for n = 1..210</a> %F A297502 Empirical: a(n) = 2*a(n-1) +19*a(n-2) +58*a(n-3) -7*a(n-4) -41*a(n-5) -196*a(n-6) -202*a(n-7) -78*a(n-8) +196*a(n-9) +176*a(n-10) +122*a(n-11) +19*a(n-12) +37*a(n-13) +22*a(n-14) +21*a(n-15) +10*a(n-16) -a(n-17) -a(n-18) %e A297502 Some solutions for n=6 %e A297502 ..1..1..1..0. .1..1..1..0. .0..1..0..0. .0..1..1..0. .0..1..0..0 %e A297502 ..0..1..0..0. .0..0..0..1. .1..1..0..0. .0..0..0..0. .1..0..0..1 %e A297502 ..0..1..0..1. .1..1..0..0. .1..0..0..1. .0..1..0..0. .0..0..1..0 %e A297502 ..1..0..1..0. .0..0..1..0. .0..0..1..0. .0..1..1..0. .0..0..0..1 %e A297502 ..0..0..0..0. .0..0..1..0. .1..0..0..0. .0..0..1..0. .0..1..1..0 %e A297502 ..1..1..0..0. .1..1..0..0. .1..1..0..0. .1..1..0..0. .0..0..1..0 %Y A297502 Cf. A297506. %K A297502 nonn %O A297502 1,1 %A A297502 _R. H. Hardin_, Dec 31 2017