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A297860
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Number of n X 2 0..1 arrays with every element equal to 2, 3 or 4 king-move adjacent elements, with upper left element zero.
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4
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0, 1, 2, 5, 10, 25, 54, 125, 282, 641, 1454, 3301, 7490, 17001, 38582, 87565, 198730, 451025, 1023614, 2323125, 5272402, 11965881, 27156934, 61633501, 139879130, 317460001, 720485262, 1635163525, 3711054050, 8422351625, 19114786774
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OFFSET
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1,3
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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-2) + 4*a(n-3) + 2*a(n-4).
Empirical g.f.: x^2*(1 + 2*x + 2*x^2) / ((1 + x)*(1 - x - 2*x^2 - 2*x^3)). - Colin Barker, Feb 21 2018
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EXAMPLE
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Some solutions for n=7:
..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..0. .1..0. .1..0. .1..0. .0..0. .0..0. .0..0. .0..0
..1..1. .1..1. .0..1. .1..1. .1..1. .1..1. .1..1. .1..1. .1..1. .1..1
..1..1. .1..1. .1..1. .0..0. .0..0. .1..0. .1..0. .1..1. .0..1. .1..0
..0..0. .0..0. .1..1. .0..1. .0..0. .0..0. .0..0. .0..0. .0..0. .0..0
..0..1. .0..1. .0..1. .1..1. .1..1. .1..0. .0..1. .1..0. .1..1. .1..0
..1..1. .1..1. .0..0. .1..1. .1..1. .1..1. .1..1. .1..1. .1..1. .1..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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