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A297909
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Number of n X 2 0..1 arrays with every element equal to 0, 2, 3 or 4 king-move adjacent elements, with upper left element zero.
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5
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1, 5, 12, 37, 104, 301, 864, 2485, 7144, 20541, 59056, 169797, 488184, 1403597, 4035520, 11602645, 33359112, 95911773, 275758800, 792842341, 2279524632, 6553929197, 18843397088, 54177212405, 155766517544, 447848955517
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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) = 5*a(n-2) + 8*a(n-3) + 4*a(n-4).
Empirical g.f.: x*(1 + 5*x + 7*x^2 + 4*x^3) / ((1 + x)*(1 - x - 4*x^2 - 4*x^3)). - Colin Barker, Feb 21 2018
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EXAMPLE
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Some solutions for n=7:
..0..1. .0..1. .0..1. .0..0. .0..0. .0..1. .0..1. .0..1. .0..1. .0..0
..1..1. .1..1. .1..1. .1..0. .1..0. .0..0. .1..1. .1..1. .1..1. .0..1
..1..0. .0..0. .1..0. .1..1. .1..1. .0..1. .1..1. .1..1. .0..0. .0..0
..0..0. .0..1. .1..1. .1..1. .0..1. .0..0. .0..1. .0..0. .1..0. .1..0
..0..1. .1..1. .0..0. .1..0. .0..0. .0..1. .1..1. .0..0. .0..0. .1..1
..1..1. .1..0. .1..0. .1..1. .0..1. .1..1. .1..0. .1..0. .1..1. .0..0
..1..1. .0..0. .1..1. .0..1. .1..1. .1..1. .0..0. .1..1. .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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