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A304770
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Number of n X 3 0..1 arrays with every element unequal to 0, 1, 2, 3 or 7 king-move adjacent elements, with upper left element zero.
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1
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4, 21, 27, 67, 139, 303, 685, 1511, 3316, 7349, 16265, 35899, 79332, 175408, 387618, 856555, 1893162, 4184055, 9246710, 20435743, 45164387, 99815208, 220596189, 487529334, 1077464178, 2381248108, 5262677458, 11630780579, 25704601383
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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) = a(n-1) +a(n-2) +3*a(n-3) +2*a(n-4) -a(n-5) for n>8.
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EXAMPLE
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Some solutions for n=5
..0..1..1. .0..0..1. .0..1..0. .0..0..1. .0..1..1. .0..1..1. .0..0..0
..0..1..1. .0..0..0. .1..1..1. .0..0..0. .1..1..1. .0..0..1. .0..1..0
..1..0..1. .0..0..0. .1..1..1. .0..0..0. .1..1..1. .0..0..0. .0..0..1
..1..1..1. .0..0..0. .1..1..1. .1..0..0. .0..1..1. .0..0..0. .0..1..0
..1..1..1. .1..1..1. .1..1..0. .1..1..0. .0..0..1. .1..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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