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 A274747 #4 Jul 04 2016 10:17:31 %S A274747 16,164,2017,25585,327123,4190533,53680592,687685512,8809672678, %T A274747 112857546696,1445776873145,18521322045287,237269920345659, %U A274747 3039578666135430,38938936908037372,498832560169009277 %N A274747 Number of nX6 0..2 arrays with no element equal to any value at offset (-1,-2) (0,-1) or (-1,0) and new values introduced in order 0..2. %C A274747 Column 6 of A274749. %H A274747 R. H. Hardin, <a href="/A274747/b274747.txt">Table of n, a(n) for n = 1..210</a> %F A274747 Empirical: a(n) = 14*a(n-1) -10*a(n-2) -80*a(n-3) +177*a(n-4) -152*a(n-5) +56*a(n-6) -a(n-7) -5*a(n-8) +a(n-9) for n>11 %e A274747 Some solutions for n=4 %e A274747 ..0..1..2..1..0..2. .0..1..2..1..0..1. .0..1..2..1..2..1. .0..1..0..1..0..1 %e A274747 ..1..0..1..0..1..0. .1..0..1..0..1..0. .1..2..1..2..1..2. .1..0..1..2..1..2 %e A274747 ..0..1..0..2..0..2. .0..1..2..1..0..2. .2..0..2..1..0..1. .0..1..2..1..0..1 %e A274747 ..2..0..1..0..2..1. .2..0..1..0..1..0. .0..2..0..2..1..0. .1..2..1..0..1..0 %Y A274747 Cf. A274749. %K A274747 nonn %O A274747 1,1 %A A274747 _R. H. Hardin_, Jul 04 2016