A220997 Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor.

3, 31, 306, 2989, 29135, 283872, 2765627, 26943707, 262494146, 2557299561, 24914003827, 242719929760, 2364652602239, 23037176752223, 224435298485050, 2186518067974709, 21301735038155095, 207528088736659200

Offset

1,1

Comments

Column 2 of A221001.

Links

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

Formula

Empirical: a(n) = 11*a(n-1) - 11*a(n-2) - 12*a(n-3) - 2*a(n-4).

Empirical g.f.: x*(3 - 2*x - 2*x^2) / (1 - 11*x + 11*x^2 + 12*x^3 + 2*x^4). - Colin Barker, Feb 23 2018

Example

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

Crossrefs

Cf. A221001.

Sequence in context: A112425 A144579 A348709 * A222094 A069589 A222090

Adjacent sequences: A220994 A220995 A220996 * A220998 A220999 A221000

Keyword

nonn

Author

R. H. Hardin, Dec 28 2012

Status

approved