A275178 Number of n X 3 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,0) or (-1,1) and new values introduced in order 0..2.

5, 16, 25, 41, 85, 181, 389, 834, 1781, 3799, 8110, 17328, 37032, 79130, 169059, 361178, 771648, 1648657, 3522441, 7525825, 16079113, 34353402, 73396957, 156814715, 335039190, 715820740, 1529371036, 3267543982, 6981199507

Offset: 1

Author

R. H. Hardin, Jul 19 2016

Keywords

• nonn

Examples

			Some solutions for n=4:
..0..0..1. .0..0..1. .0..1..2. .0..0..1. .0..0..1. .0..0..0. .0..0..1
..2..2..0. .2..2..0. .2..0..1. .2..2..0. .2..2..2. .1..2..2. .2..2..0
..1..1..2. .0..1..2. .1..2..2. .0..1..1. .1..1..1. .0..1..1. .1..1..1
..0..0..1. .2..0..1. .0..0..1. .2..0..0. .2..0..0. .2..2..0. .0..0..0
		

Links

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

Crossrefs

Column 3 of A275183.

Formula

Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 5*a(n-3) - a(n-4) - a(n-5) for n>8.

Empirical g.f.: x*(5 - 4*x - 9*x^2 + 12*x^3 - 4*x^4 - 17*x^5 + 11*x^6 + 5*x^7) / ((1 - x)*(1 - 3*x + 3*x^2 - 2*x^3 - x^4)). - Colin Barker, Feb 01 2019