A221196 Number of n X 3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with no occupancy greater than 2.

2, 10, 46, 212, 976, 4492, 20672, 95128, 437752, 2014400, 9269632, 42655888, 196288736, 903257824, 4156502752, 19126892096, 88015820416, 405020564416, 1863774679808, 8576493051520, 39466269101440, 181611106939904

Offset: 1

Author

R. H. Hardin, Jan 04 2013

Keywords

• nonn

Comments

Column 3 of A221200.

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..33

Crossrefs

Cf. A221200.

Formula

Empirical: a(n) = 6*a(n-1) - 6*a(n-2) - 2*a(n-3).

Empirical g.f.: 2*x*(1 - x - x^2) / (1 - 6*x + 6*x^2 + 2*x^3). - Colin Barker, Aug 04 2018