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 A275140 #8 Jan 31 2019 19:36:52 %S A275140 16,432,1216,6464,32384,165568,841536,4283968,21800000,110943552, %T A275140 564600384,2873300800,14622480448,74415076672,378704836160, %U A275140 1927261993792,9808004727872,49913793159488,254015655387712,1292707868694336 %N A275140 Number of n X 6 0..2 arrays with no element equal to any value at offset (-2,-2) (-1,-2) or (0,-1) and new values introduced in order 0..2. %H A275140 R. H. Hardin, <a href="/A275140/b275140.txt">Table of n, a(n) for n = 1..210</a> %F A275140 Empirical: a(n) = 3*a(n-1) + 10*a(n-2) + 4*a(n-3) - 4*a(n-4) for n>6. %F A275140 Empirical g.f.: 16*x*(1 + 24*x - 15*x^2 - 98*x^3 - 52*x^4 + 40*x^5) / (1 - 3*x - 10*x^2 - 4*x^3 + 4*x^4). - _Colin Barker_, Jan 31 2019 %e A275140 Some solutions for n=5: %e A275140 ..0..1..2..1..0..2. .0..1..2..0..1..2. .0..1..2..1..0..2. .0..1..2..0..1..0 %e A275140 ..2..1..2..0..1..0. .0..1..2..0..1..2. .2..1..2..0..1..2. .0..1..2..0..1..2 %e A275140 ..2..0..1..2..1..2. .2..0..1..2..1..2. .1..0..1..2..0..2. .2..0..1..2..0..1 %e A275140 ..2..0..1..2..0..1. .1..0..1..2..0..1. .1..2..0..2..0..1. .1..2..1..2..0..1 %e A275140 ..0..2..0..1..0..1. .0..2..0..1..2..0. .0..2..0..1..2..1. .2..1..0..1..0..1 %Y A275140 Column 6 of A275142. %K A275140 nonn %O A275140 1,1 %A A275140 _R. H. Hardin_, Jul 17 2016