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.

16, 432, 1216, 6464, 32384, 165568, 841536, 4283968, 21800000, 110943552, 564600384, 2873300800, 14622480448, 74415076672, 378704836160, 1927261993792, 9808004727872, 49913793159488, 254015655387712, 1292707868694336

Offset: 1

Author

R. H. Hardin, Jul 17 2016

Keywords

• nonn

Examples

			Some solutions for n=5:
..0..1..2..1..0..2. .0..1..2..0..1..2. .0..1..2..1..0..2. .0..1..2..0..1..0
..2..1..2..0..1..0. .0..1..2..0..1..2. .2..1..2..0..1..2. .0..1..2..0..1..2
..2..0..1..2..1..2. .2..0..1..2..1..2. .1..0..1..2..0..2. .2..0..1..2..0..1
..2..0..1..2..0..1. .1..0..1..2..0..1. .1..2..0..2..0..1. .1..2..1..2..0..1
..0..2..0..1..0..1. .0..2..0..1..2..0. .0..2..0..1..2..1. .2..1..0..1..0..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Column 6 of A275142.

Formula

Empirical: a(n) = 3*a(n-1) + 10*a(n-2) + 4*a(n-3) - 4*a(n-4) for n>6.

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