A221404 Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, with every occupancy equal to zero or two.

0, 16, 0, 436, 0, 12668, 0, 368268, 0, 10705360, 0, 311197280, 0, 9046269888, 0, 262968117056, 0, 7644280337936, 0, 222213327464336, 0, 6459569820912704, 0, 187774705858714240, 0, 5458465675503960896, 0, 158673381440822516672, 0

Offset: 1

Author

R. H. Hardin Jan 15 2013

Keywords

• nonn

Comments

Column 3 of A221408

Examples

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

Links

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

Formula

Empirical: a(n) = 36*a(n-2) -200*a(n-4) -40*a(n-6) -84*a(n-8) +80*a(n-10) -20*a(n-12) +80*a(n-14)