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A221414
Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with every occupancy equal to zero or two
1
0, 10, 0, 150, 0, 2250, 0, 33750, 0, 506250, 0, 7593750, 0, 113906250, 0, 1708593750, 0, 25628906250, 0, 384433593750, 0, 5766503906250, 0, 86497558593750, 0, 1297463378906250, 0, 19461950683593750, 0, 291929260253906250, 0
OFFSET
1,2
COMMENTS
Column 3 of A221419
LINKS
FORMULA
Empirical: a(n) = 15*a(n-2)
EXAMPLE
Some solutions for n=4
..0..2..0....2..2..0....0..2..2....2..0..0....2..2..0....2..0..0....0..2..2
..2..2..0....0..2..0....0..2..0....0..2..2....0..0..2....0..2..0....0..2..0
..2..2..0....2..0..2....0..2..0....2..0..0....2..0..0....2..2..0....2..0..0
..0..0..2....0..2..0....2..2..0....0..2..2....2..2..0....2..2..0....2..2..0
CROSSREFS
Sequence in context: A285536 A285477 A089831 * A326719 A070190 A216797
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 15 2013
STATUS
approved