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A221306
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Number of nX4 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, with every occupancy equal to zero or two
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1
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1, 31, 312, 3334, 38146, 431474, 4855258, 54587829, 613235478, 6885012344, 77275657244, 867163601744, 9729984671155, 109168050158528, 1224793149317547, 13741066811792010, 154160315091605934, 1729503583940965893
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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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EXAMPLE
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Some solutions for n=3
..0..2..2..0....0..0..0..2....2..0..0..0....0..2..0..2....0..0..2..0
..2..0..2..2....2..2..2..2....2..2..2..0....2..0..0..2....2..2..2..0
..0..2..0..0....0..0..0..2....2..0..2..0....0..2..2..0....2..0..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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