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A221730
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Number of 4 X n arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.
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0
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0, 44, 464, 6188, 80160, 1048566, 13757056, 180437354, 2363318964, 30930073844, 404584067882, 5290050421396
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OFFSET
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1,2
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LINKS
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EXAMPLE
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Some solutions for n=3:
..2..2..0....2..0..2....2..2..0....0..0..2....0..0..2....0..2..0....0..2..0
..0..2..0....2..0..0....0..0..2....2..2..0....2..2..2....2..0..2....0..0..2
..0..0..2....0..2..0....2..2..0....2..2..0....0..2..0....0..2..2....2..2..0
..2..2..0....2..2..0....0..2..0....0..0..2....0..0..2....0..0..2....2..0..2
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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