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 A269213 #4 Feb 20 2016 11:28:58 %S A269213 5832,2546304,1012764384,354189986208,116322554833728, %T A269213 36713945487331392,11273191243423937904,3392211859561264876416, %U A269213 1005065652737890110097824,294164506851983123928014976,85246917739611183231260455872 %N A269213 Number of nX7 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once. %C A269213 Column 7 of A269214. %H A269213 R. H. Hardin, <a href="/A269213/b269213.txt">Table of n, a(n) for n = 1..210</a> %e A269213 Some solutions for n=1 %e A269213 ..0..0..0..0..3..1..3. .1..0..2..0..3..3..1. .2..3..2..2..1..0..1 %Y A269213 Cf. A269214. %K A269213 nonn %O A269213 1,1 %A A269213 _R. H. Hardin_, Feb 20 2016