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 A269055 #4 Feb 18 2016 11:41:11 %S A269055 81,666,3258,24192,149358,971844,6053094,37741920,231943614, %T A269055 1417576284,8599619586,51899214960,311654917170,1863739501308, %U A269055 11103704855298,65935768579488,390381077316294,2305171593612444,13579182450069246 %N A269055 Number of 4Xn 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. %C A269055 Row 4 of A269052. %H A269055 R. H. Hardin, <a href="/A269055/b269055.txt">Table of n, a(n) for n = 1..210</a> %F A269055 Empirical: a(n) = 6*a(n-1) +23*a(n-2) -102*a(n-3) -288*a(n-4) +250*a(n-5) +787*a(n-6) -238*a(n-7) -741*a(n-8) +124*a(n-9) +196*a(n-10) -16*a(n-11) -16*a(n-12) for n>14 %e A269055 Some solutions for n=4 %e A269055 ..0..0..1..2. .1..2..1..0. .1..2..1..0. .2..2..2..2. .1..0..1..2 %e A269055 ..1..0..1..0. .0..0..1..0. .2..2..2..2. .2..2..1..0. .1..2..1..2 %e A269055 ..1..2..1..2. .1..0..1..0. .2..1..2..1. .2..2..1..0. .2..2..2..2 %e A269055 ..1..0..2..2. .1..0..0..0. .2..1..0..1. .1..2..1..2. .1..1..2..1 %Y A269055 Cf. A269052. %K A269055 nonn %O A269055 1,1 %A A269055 _R. H. Hardin_, Feb 18 2016