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 A269279 #4 Feb 21 2016 08:59:59 %S A269279 0,20412,1365336,74853576,3719884392,174924572760,7934992835112, %T A269279 350946381867480,15232155757251048,651580499598523992, %U A269279 27551808205246504872,1154085846201751972824,47965168186749101620584 %N A269279 Number of 4Xn 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three exactly once. %C A269279 Row 4 of A269276. %H A269279 R. H. Hardin, <a href="/A269279/b269279.txt">Table of n, a(n) for n = 1..210</a> %F A269279 Empirical: a(n) = 96*a(n-1) -3108*a(n-2) +40720*a(n-3) -265326*a(n-4) +931200*a(n-5) -1766452*a(n-6) +1678992*a(n-7) -622521*a(n-8) for n>12 %e A269279 Some solutions for n=2 %e A269279 ..0..3. .2..0. .1..3. .1..3. .0..2. .0..2. .0..1. .0..2. .0..1. .1..3 %e A269279 ..3..3. .0..0. .0..0. .3..1. .3..3. .3..2. .3..2. .2..3. .3..1. .2..2 %e A269279 ..2..2. .1..3. .2..2. .2..2. .0..2. .1..0. .0..1. .3..2. .3..0. .1..3 %e A269279 ..0..2. .1..2. .0..1. .3..2. .2..3. .0..2. .1..2. .1..3. .0..0. .1..1 %Y A269279 Cf. A269276. %K A269279 nonn %O A269279 1,2 %A A269279 _R. H. Hardin_, Feb 21 2016