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 A269207 #4 Feb 20 2016 10:34:03 %S A269207 16384,8787660,2380537188,672230393004,179867149105740, %T A269207 47121391706947500,12093315071771856492,3057161412747926879388, %U A269207 763401355846887190121676,188738443220730807440394588,46278051540027048274339056012 %N A269207 Number of 7Xn 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three no more than once. %C A269207 Row 7 of A269201. %H A269207 R. H. Hardin, <a href="/A269207/b269207.txt">Table of n, a(n) for n = 1..210</a> %e A269207 Some solutions for n=2 %e A269207 ..0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0 %e A269207 ..0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0 %e A269207 ..2..2. .1..0. .0..1. .3..1. .0..1. .0..0. .0..0. .2..0. .1..1. .2..2 %e A269207 ..0..2. .0..0. .0..0. .3..2. .0..1. .2..0. .0..0. .2..2. .1..3. .2..0 %e A269207 ..2..1. .2..2. .2..0. .0..1. .3..1. .2..2. .0..2. .1..0. .1..3. .2..0 %e A269207 ..0..2. .1..3. .2..3. .0..2. .3..3. .0..0. .0..0. .0..0. .3..1. .2..3 %e A269207 ..3..1. .1..3. .1..3. .3..2. .0..2. .1..1. .0..2. .2..0. .3..2. .2..3 %Y A269207 Cf. A269201. %K A269207 nonn %O A269207 1,1 %A A269207 _R. H. Hardin_, Feb 20 2016