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A303722
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Number of nX3 0..1 arrays with every element unequal to 0, 1, 2 or 3 king-move adjacent elements, with upper left element zero.
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1
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4, 21, 23, 46, 77, 151, 294, 549, 1051, 2032, 3877, 7421, 14262, 27333, 52371, 100472, 192665, 369353, 708294, 1358233, 2604287, 4993776, 9575821, 18361581, 35208486, 67513133, 129457227, 248235688, 475996017, 912729185, 1750170310, 3355977073
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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) = 2*a(n-1) +a(n-3) -2*a(n-4) -2*a(n-5) +2*a(n-6) for n>9
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EXAMPLE
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Some solutions for n=5
..0..1..0. .0..0..0. .0..1..1. .0..0..1. .0..1..1. .0..0..0. .0..1..1
..1..1..1. .1..1..1. .0..0..1. .0..0..0. .0..0..1. .0..0..0. .1..1..1
..1..1..1. .1..1..1. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .1..1..1
..1..1..1. .0..1..1. .0..0..0. .0..0..0. .0..0..1. .1..0..0. .1..1..1
..1..1..1. .0..0..1. .1..1..1. .1..0..1. .0..1..1. .1..1..0. .0..1..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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