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A304922
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Number of nX4 0..1 arrays with every element unequal to 0, 1, 2, 5 or 7 king-move adjacent elements, with upper left element zero.
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1
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8, 9, 31, 87, 266, 851, 2510, 7348, 21910, 65581, 195382, 581778, 1734115, 5169644, 15407810, 45920848, 136868173, 407941876, 1215873162, 3623912739, 10801114566, 32192856740, 95951141082, 285983353689, 852376442742, 2540517125174
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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) = 3*a(n-1) +2*a(n-3) -4*a(n-4) -6*a(n-5) -6*a(n-6) -a(n-7) +23*a(n-8) -12*a(n-9) +4*a(n-10) +8*a(n-11) -2*a(n-12) -8*a(n-13) for n>18
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EXAMPLE
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Some solutions for n=5
..0..0..1..0. .0..1..0..0. .0..0..1..0. .0..0..0..0. .0..1..0..0
..1..0..0..0. .0..0..0..1. .1..0..0..0. .1..0..0..1. .0..0..0..0
..0..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0
..0..0..0..1. .0..0..0..0. .1..0..0..0. .0..0..0..1. .1..0..0..0
..0..0..0..0. .0..0..1..0. .0..0..0..0. .0..0..0..0. .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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