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A303802
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Number of n X 2 0..1 arrays with every element unequal to 0, 1, 3 or 4 king-move adjacent elements, with upper left element zero.
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8
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2, 5, 7, 17, 35, 61, 127, 265, 507, 1013, 2071, 4097, 8147, 16429, 32815, 65401, 131115, 262373, 523975, 1048433, 2097923, 4193821, 8387551, 16779241, 33554523, 67104725, 134221687, 268439777, 536858675, 1073745421, 2147504527, 4294939225
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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) +4*a(n-3) -4*a(n-4) for n>5.
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EXAMPLE
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Some solutions for n=5
..0..1. .0..0. .0..0. .0..1. .0..0. .0..0. .0..1. .0..0. .0..1. .0..0
..0..0. .0..0. .0..0. .1..1. .0..1. .0..1. .0..0. .0..1. .1..1. .1..0
..1..1. .0..0. .1..0. .0..0. .1..1. .1..1. .0..0. .1..1. .0..0. .1..1
..0..0. .0..0. .1..1. .1..0. .1..1. .1..1. .0..0. .1..1. .1..1. .1..1
..1..0. .0..0. .1..1. .1..1. .1..1. .1..0. .0..1. .0..1. .1..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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