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 A269049 #4 Feb 18 2016 11:36:19 %S A269049 144,1068,13140,149358,1643376,17696520,187575858,1964080920, %T A269049 20365312416,209472681102,2140087086852,21738862087680, %U A269049 219728193571542,2211332610944712,22170082238167692,221519854346189046 %N A269049 Number of nX5 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. %C A269049 Column 5 of A269052. %H A269049 R. H. Hardin, <a href="/A269049/b269049.txt">Table of n, a(n) for n = 1..210</a> %F A269049 Empirical: a(n) = 28*a(n-1) -286*a(n-2) +1290*a(n-3) -2373*a(n-4) +304*a(n-5) +3551*a(n-6) -2846*a(n-7) -546*a(n-8) +1308*a(n-9) -505*a(n-10) +76*a(n-11) -4*a(n-12) for n>13 %e A269049 Some solutions for n=4 %e A269049 ..0..1..2..2..0. .2..1..2..1..2. .0..1..2..1..2. .1..2..1..0..0 %e A269049 ..0..1..2..1..2. .2..1..2..1..2. .0..0..0..1..0. .2..2..1..0..1 %e A269049 ..0..1..0..1..0. .0..1..0..1..0. .0..0..0..1..0. .1..0..1..0..1 %e A269049 ..0..1..0..1..0. .2..0..0..0..0. .0..0..0..1..2. .1..0..1..2..1 %Y A269049 Cf. A269052. %K A269049 nonn %O A269049 1,1 %A A269049 _R. H. Hardin_, Feb 18 2016