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 A269216 #4 Feb 20 2016 11:31:21 %S A269216 0,1152,18048,308544,4744704,70371048,1012764384,14272781904, %T A269216 197924795136,2710127012280,36731155605600,493646491209600, %U A269216 6587572246924800,87381895621488648,1153101183028855008 %N A269216 Number of 3Xn 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once. %C A269216 Row 3 of A269214. %H A269216 R. H. Hardin, <a href="/A269216/b269216.txt">Table of n, a(n) for n = 1..210</a> %F A269216 Empirical: a(n) = 24*a(n-1) -130*a(n-2) -248*a(n-3) +935*a(n-4) +272*a(n-5) -1768*a(n-6) +960*a(n-7) -144*a(n-8) %e A269216 Some solutions for n=3 %e A269216 ..2..3..1. .0..2..3. .0..0..0. .1..3..1. .2..2..2. .3..2..2. .0..1..0 %e A269216 ..3..1..1. .0..0..2. .2..2..3. .3..3..1. .1..0..0. .0..0..0. .1..0..2 %e A269216 ..0..1..3. .0..0..2. .2..2..0. .2..1..1. .0..0..2. .0..1..0. .0..0..2 %Y A269216 Cf. A269214. %K A269216 nonn %O A269216 1,2 %A A269216 _R. H. Hardin_, Feb 20 2016