A221730 Number of 4 X n arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.

0, 44, 464, 6188, 80160, 1048566, 13757056, 180437354, 2363318964, 30930073844, 404584067882, 5290050421396

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Example

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

Crossrefs

Row 4 of A221728.

Sequence in context: A094201 A210426 A231242 * A306036 A160150 A210119

Adjacent sequences: A221727 A221728 A221729 * A221731 A221732 A221733

Keyword

nonn,more

Author

R. H. Hardin, Jan 22 2013

Status

approved