A221241 Number of n X 3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor.

2, 50, 1056, 21660, 441720, 8997120, 183206016, 3730330800, 75953515968, 1546488223200, 31487986033920, 641125466910720, 13053925809145728, 265790370894192000, 5411745241852207104, 110188290202715208960

Offset: 1

Author

R. H. Hardin, Jan 06 2013

Keywords

• nonn

Comments

Column 3 of A221245.

Examples

			Some solutions for n=3:
..1..1..0....0..0..1....0..2..2....0..0..0....2..1..0....0..3..0....0..4..1
..1..1..1....1..4..0....0..4..1....0..5..1....0..4..0....1..3..0....0..2..0
..0..4..0....0..2..1....0..0..0....0..1..2....1..1..0....2..0..0....1..0..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..119

Crossrefs

Cf. A221245.

Formula

Empirical: a(n) = 30*a(n-1) - 222*a(n-2) + 540*a(n-3) - 324*a(n-4).

Empirical g.f.: 2*(1 - 5*x) / (1 - 30*x + 222*x^2 - 540*x^3 + 324*x^4). - Colin Barker, Aug 04 2018