A221162 Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor.

3, 33, 352, 3721, 39254, 413908, 4363921, 46008619, 485064009, 5113971944, 53915979657, 568429529006, 5992882377940, 63182219138721, 666122336505939, 7022845559348401, 74040993741513520, 780605056433123273

Offset

1,1

Comments

Column 2 of A221165.

Links

R. H. Hardin, Table of n, a(n) for n = 1..23

Formula

Empirical: a(n) = 13*a(n-1) - 26*a(n-2) + a(n-3).

Empirical g.f.: x*(3 - 6*x + x^2) / (1 - 13*x + 26*x^2 - x^3). - Colin Barker, Aug 04 2018

Example

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

Crossrefs

Cf. A221165.

Sequence in context: A002277 A332087 A001507 * A231594 A075835 A077698

Adjacent sequences: A221159 A221160 A221161 * A221163 A221164 A221165

Keyword

nonn

Author

R. H. Hardin, Jan 03 2013

Status

approved