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A221414
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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
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1
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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
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 15*a(n-2)
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EXAMPLE
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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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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