A220999 Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor.

21, 2989, 394580, 51672851, 6758547145, 883809591160, 115571009291599, 15112491898694315, 1976162121051496204, 258409744432367037405, 33790541796768618273627, 4418566652828051992947794

Offset: 1

Author

R. H. Hardin Dec 28 2012

Keywords

• nonn

Comments

Column 4 of A221001

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..19