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 A274894 #4 Jul 10 2016 20:00:22 %S A274894 32,972,465,2291,10337,49697,237807,1143185,5539989,26833885, %T A274894 130079497,632358111,3069896886,14919608999,72537188422,352492355625, %U A274894 1713947371548,8332597817985,40508772974972,196969575853783,957632906229433 %N A274894 Number of nX7 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-1) or (-2,0) and new values introduced in order 0..2. %C A274894 Column 7 of A274895. %H A274894 R. H. Hardin, <a href="/A274894/b274894.txt">Table of n, a(n) for n = 1..210</a> %e A274894 Some solutions for n=4 %e A274894 ..0..1..2..0..1..0..1. .0..1..0..2..1..0..1. .0..1..2..0..2..0..1 %e A274894 ..1..2..0..1..2..0..2. .2..1..0..2..0..2..1. .0..1..2..1..2..0..1 %e A274894 ..1..2..0..2..0..1..2. .1..0..2..1..0..1..0. .1..2..0..1..0..1..2 %e A274894 ..2..0..1..2..1..2..0. .1..0..2..1..2..1..0. .1..2..1..2..0..1..2 %Y A274894 Cf. A274895. %K A274894 nonn %O A274894 1,1 %A A274894 _R. H. Hardin_, Jul 10 2016