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A305225
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Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 3 or 8 king-move adjacent elements, with upper left element zero.
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1
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4, 21, 24, 54, 108, 236, 509, 1091, 2363, 5109, 11034, 23867, 51606, 111571, 241263, 521680, 1128006, 2439107, 5274072, 11404090, 24659080, 53320283, 115294335, 249300825, 539062799, 1165614674, 2520407019, 5449872468, 11784251403
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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-2) -3*a(n-4) -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..0..0. .0..0..1. .0..1..1. .0..0..0. .0..0..0. .0..0..0. .0..1..1
..1..1..1. .0..0..0. .1..1..1. .0..0..0. .0..0..0. .0..0..0. .0..0..1
..1..1..1. .0..1..0. .1..0..1. .0..0..0. .0..0..1. .0..0..0. .0..0..0
..0..1..1. .0..0..0. .1..1..1. .0..1..0. .0..1..1. .1..1..1. .0..0..1
..0..0..1. .0..0..1. .0..1..0. .0..0..0. .1..1..1. .1..1..1. .0..1..1
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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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