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A221395
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Number of nX4 arrays of occupancy after each element stays put or 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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4, 54, 631, 7678, 93398, 1137850, 13857444, 168717375, 2053766992, 24997337148, 304235229651, 3702632940296, 45061321786573, 548394286665966, 6673898631211550, 81220384265578677, 988438827804013263
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OFFSET
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1,1
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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....2..2..0..2....2..0..2..0....2..2..0..0....0..2..2..2
..0..2..2..0....2..0..2..2....2..2..0..2....2..2..2..2....2..0..0..0
..0..2..0..2....0..0..0..0....0..2..0..0....0..0..0..0....0..0..2..2
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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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