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 A269083 #8 Jan 19 2019 03:15:05 %S A269083 4,11,30,76,191,467,1127,2686,6339,14840,34504,79759,183445,420077, %T A269083 958248,2178427,4937234,11159252,25160111,56599879,127066227, %U A269083 284728994,636922003,1422499564,3172350160,7065116255,15714769641,34912773337 %N A269083 Number of n X 2 binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once. %H A269083 R. H. Hardin, <a href="/A269083/b269083.txt">Table of n, a(n) for n = 1..210</a> %F A269083 Empirical: a(n) = 2*a(n-1) + 3*a(n-2) - 2*a(n-3) - 6*a(n-4) - 4*a(n-5) - a(n-6). %F A269083 Empirical g.f.: x*(4 + 3*x - 4*x^2 - 9*x^3 - 5*x^4 - x^5) / (1 - x - 2*x^2 - x^3)^2. - _Colin Barker_, Jan 19 2019 %e A269083 Some solutions for n=4: %e A269083 ..1..0. .0..0. .0..0. .0..1. .0..1. .0..0. .0..0. .0..0. .0..1. .0..0 %e A269083 ..1..0. .1..1. .1..1. .0..0. .1..0. .1..0. .0..1. .0..1. .0..1. .0..1 %e A269083 ..0..1. .0..0. .0..0. .1..0. .0..1. .1..0. .0..0. .0..0. .0..0. .0..0 %e A269083 ..0..0. .0..1. .0..0. .0..0. .0..0. .0..0. .0..0. .1..0. .0..1. .0..1 %Y A269083 Column 2 of A269089. %K A269083 nonn %O A269083 1,1 %A A269083 _R. H. Hardin_, Feb 19 2016