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A282310
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Number of n X 2 0..1 arrays with no 1 equal to more than four of its king-move neighbors.
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1
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4, 16, 63, 249, 984, 3888, 15363, 60705, 239868, 947808, 3745143, 14798457, 58474224, 231053472, 912978459, 3607518465, 14254651188, 56325444336, 222562841967, 879428812473, 3474951296328, 13730828852304, 54255626883315
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + 3*a(n-3).
Empirical g.f.: x*(4 + 4*x + 3*x^2) / (1 - 3*x - 3*x^2 - 3*x^3). - Colin Barker, Feb 20 2019
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EXAMPLE
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Some solutions for n=4:
..0..1. .0..1. .1..0. .1..1. .1..1. .1..0. .1..0. .0..0. .1..1. .1..0
..0..0. .1..0. .0..1. .1..1. .0..1. .1..0. .1..1. .1..1. .1..1. .1..1
..0..1. .0..1. .0..0. .1..0. .0..1. .0..0. .1..1. .0..0. .0..0. .0..1
..0..0. .0..1. .1..0. .1..0. .0..1. .1..0. .1..0. .0..0. .1..1. .0..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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