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 A276247 #4 Aug 25 2016 11:03:19 %S A276247 48,1944,9148,115682,1423062,17450554,219977330,2780927371, %T A276247 35144231606,446083313365,5668147759489,72021229704285, %U A276247 915757509022000,11646919947937198,148122094309974829,1883921138963266109 %N A276247 Number of nX7 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,1) or (0,-2) and new values introduced in order 0..2. %C A276247 Column 7 of A276248. %H A276247 R. H. Hardin, <a href="/A276247/b276247.txt">Table of n, a(n) for n = 1..210</a> %e A276247 Some solutions for n=4 %e A276247 ..0..0..1..1..2..0..1. .0..1..1..0..2..1..1. .0..0..1..1..2..0..0 %e A276247 ..1..2..0..0..2..2..0. .0..2..2..1..0..0..2. .1..2..0..0..1..2..0 %e A276247 ..0..1..2..0..0..1..1. .1..1..0..2..2..0..0. .0..1..2..2..0..1..2 %e A276247 ..0..0..1..2..2..0..0. .2..1..1..0..2..2..1. .2..0..0..1..2..0..0 %Y A276247 Cf. A276248. %K A276247 nonn %O A276247 1,1 %A A276247 _R. H. Hardin_, Aug 25 2016