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 A269013 #8 Jan 18 2019 09:58:24 %S A269013 0,15,46,305,1078,4948,18210,73277,270458,1026795,3757996,13847240, %T A269013 50155940,181596651,651546278,2331910405,8300115170,29460799452, %U A269013 104176325510,367430075801,1292287850546,4534933300095,15878737307224 %N A269013 Number of 3 X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once. %H A269013 R. H. Hardin, <a href="/A269013/b269013.txt">Table of n, a(n) for n = 1..210</a> %F A269013 Empirical: a(n) = 4*a(n-1) + 8*a(n-2) - 34*a(n-3) - 16*a(n-4) + 60*a(n-5) - 25*a(n-6). %F A269013 Empirical g.f.: x^2*(15 - 14*x + x^2) / (1 - 2*x - 6*x^2 + 5*x^3)^2. - _Colin Barker_, Jan 18 2019 %e A269013 Some solutions for n=4: %e A269013 ..1..1..0..1. .0..0..0..0. .1..0..0..0. .1..0..0..0. .0..1..0..1 %e A269013 ..0..0..0..0. .1..1..0..0. .0..0..0..0. .1..0..1..0. .1..0..0..0 %e A269013 ..1..0..0..0. .0..0..0..1. .1..1..0..0. .1..0..0..1. .0..0..0..0 %Y A269013 Row 3 of A269011. %K A269013 nonn %O A269013 1,2 %A A269013 _R. H. Hardin_, Feb 17 2016