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 A269006 #7 Jan 18 2019 06:33:23 %S A269006 2,8,46,224,1066,4952,22654,102416,458674,2038328,8999374,39512144, %T A269006 172645498,751190504,3256354942,14069557088,60610482274,260412843944, %U A269006 1116181074286,4773749750528,20376053362762,86813692172216 %N A269006 Number of n X 3 binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once. %H A269006 R. H. Hardin, <a href="/A269006/b269006.txt">Table of n, a(n) for n = 1..210</a> %F A269006 Empirical: a(n) = 10*a(n-1) - 31*a(n-2) + 24*a(n-3) + 21*a(n-4) - 18*a(n-5) - 9*a(n-6). %F A269006 Empirical g.f.: 2*x*(1 - x)*(1 - 3*x)*(1 - 2*x + 3*x^2) / (1 - 5*x + 3*x^2 + 3*x^3)^2. - _Colin Barker_, Jan 18 2019 %e A269006 Some solutions for n=4: %e A269006 ..1..0..0. .1..0..1. .1..0..1. .0..1..1. .1..0..0. .0..1..1. .0..1..0 %e A269006 ..1..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .1..0..0 %e A269006 ..1..0..0. .0..0..0. .0..0..1. .0..0..1. .0..0..0. .0..0..0. .0..0..0 %e A269006 ..0..1..0. .1..1..0. .0..1..0. .0..0..0. .1..0..0. .1..0..1. .1..0..0 %Y A269006 Column 3 of A269011. %K A269006 nonn %O A269006 1,1 %A A269006 _R. H. Hardin_, Feb 17 2016