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

Author

R. H. Hardin, Jan 22 2013

Keywords

• nonn
• more

Examples

			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.