A208195 Number of n X 2 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or left-upward diagonal neighbors.

2, 14, 178, 2653, 41272, 648569, 10215440, 160984657, 2537249104, 39990174809, 630298266416, 9934351303777, 156578831693200, 2467894630281641, 38897365218137072, 613075213064694577, 9662896575843028048

Offset: 1

Author

R. H. Hardin, Feb 24 2012

Keywords

• nonn

Comments

Column 2 of A208201.

Examples

			Some solutions for n=4:
..0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..0....0..1
..0..1....1..0....1..1....1..0....1..0....0..1....1..1....0..1....0..1....1..0
..0..0....2..0....0..1....1..0....0..0....0..0....0..0....0..2....1..0....0..0
..1..2....1..2....0..0....0..1....0..1....0..2....0..1....1..3....2..2....2..0
		

Links

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

Crossrefs

Cf. A208201.

Formula

Empirical: a(n) = 18*a(n-1) - 31*a(n-2) - 66*a(n-3) - 24*a(n-4) for n>5.

Empirical g.f.: x*(2 - 22*x - 12*x^2 + 15*x^3 + 8*x^4) / ((1 - 3*x - 2*x^2)*(1 - 15*x - 12*x^2)). - Colin Barker, Jun 29 2018