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 A269219 #4 Feb 20 2016 11:33:48 %S A269219 0,889056,118872576,17118725376,2267772823680,292321215814512, %T A269219 36713945487331392,4528086446983948224,550465224463202188320, %U A269219 66156064863501806179776,7876627077577027391888640 %N A269219 Number of 6Xn 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once. %C A269219 Row 6 of A269214. %H A269219 R. H. Hardin, <a href="/A269219/b269219.txt">Table of n, a(n) for n = 1..210</a> %e A269219 Some solutions for n=2 %e A269219 ..0..2. .0..0. .0..0. .0..0. .0..1. .0..0. .0..0. .0..1. .0..0. .0..2 %e A269219 ..0..1. .2..3. .0..1. .0..2. .0..0. .0..2. .0..2. .0..1. .0..0. .0..0 %e A269219 ..3..1. .3..2. .1..1. .3..2. .3..1. .2..0. .2..2. .3..2. .2..3. .0..2 %e A269219 ..3..3. .2..2. .1..3. .3..3. .0..2. .2..2. .3..2. .0..3. .2..0. .3..0 %e A269219 ..2..3. .2..0. .2..1. .1..2. .0..1. .1..0. .3..1. .3..1. .0..0. .2..3 %e A269219 ..3..0. .1..3. .3..2. .2..3. .3..2. .1..1. .0..0. .3..3. .0..2. .3..2 %Y A269219 Cf. A269214. %K A269219 nonn %O A269219 1,2 %A A269219 _R. H. Hardin_, Feb 20 2016