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

1,1

Comments

Column 3 of A221245.

Links

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

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

Example

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

Crossrefs

Cf. A221245.

Sequence in context: A083939 A083941 A080263 * A246071 A367777 A088920

Adjacent sequences: A221238 A221239 A221240 * A221242 A221243 A221244

Keyword

nonn

Author

R. H. Hardin, Jan 06 2013

Status

approved