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A268974
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Number of 4Xn 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
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1
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81, 1728, 15552, 136080, 1125360, 9093528, 72081792, 563173128, 4349328912, 33272350344, 252534743280, 1904015932416, 14274182767248, 106487231224248, 791006745522096, 5853579437553624, 43172409083833728, 317460508504648992
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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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FORMULA
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Empirical: a(n) = 18*a(n-1) -111*a(n-2) +282*a(n-3) -333*a(n-4) +180*a(n-5) -36*a(n-6) for n>12
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EXAMPLE
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Some solutions for n=4
..2..1..0..0. .0..0..1..2. .0..1..0..0. .2..1..0..0. .0..1..2..1
..0..0..1..2. .0..2..1..2. .0..0..0..0. .0..0..0..0. .2..1..0..0
..1..2..2..2. .1..0..1..0. .2..1..0..0. .1..0..1..1. .0..0..1..2
..2..1..0..0. .0..0..0..0. .2..1..0..1. .1..0..0..0. .1..0..0..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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