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A297817
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Number of nX2 0..1 arrays with every element equal to 1, 2 or 3 king-move adjacent elements, with upper left element zero.
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5
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1, 4, 17, 49, 166, 573, 1933, 6538, 22165, 75089, 254350, 861661, 2919029, 9888610, 33499125, 113483321, 384441606, 1302353053, 4411914717, 14946017274, 50631856149, 171522942625, 581059476926, 1968425392285, 6668333757637
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) +a(n-2) +2*a(n-3) -2*a(n-4) -4*a(n-5) for n>6
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EXAMPLE
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Some solutions for n=7
..0..1. .0..0. .0..1. .0..0. .0..1. .0..1. .0..0. .0..0. .0..1. .0..1
..1..0. .1..1. .0..1. .1..1. .1..0. .0..1. .1..0. .1..0. .1..0. .0..1
..1..0. .0..0. .0..1. .1..0. .1..1. .0..0. .0..1. .1..0. .0..0. .1..0
..1..1. .0..0. .0..1. .0..0. .0..0. .0..1. .0..0. .0..0. .0..1. .0..1
..1..0. .1..1. .0..1. .1..0. .1..0. .0..1. .1..0. .1..0. .1..0. .0..1
..0..1. .0..1. .0..1. .1..0. .1..0. .0..1. .1..0. .0..1. .0..0. .1..0
..1..0. .0..1. .0..1. .1..0. .0..1. .0..1. .0..1. .0..1. .1..1. .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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