A221404 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Column 3 of A221408

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)

EXAMPLE

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