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A296733
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Number of n X 2 0..1 arrays with each 1 adjacent to 1, 2 or 4 king-move neighboring 1s.
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1
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2, 11, 31, 88, 287, 881, 2686, 8347, 25763, 79376, 245227, 757045, 2336222, 7212287, 22263871, 68722504, 212138639, 654844841, 2021399374, 6239772643, 19261292171, 59456768000, 183534426499, 566544237805, 1748839677662, 5398414303799
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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) - a(n-2) + 8*a(n-3) - 12*a(n-4) + 2*a(n-5) - 12*a(n-6).
Empirical g.f.: x*(2 + x + 2*x^2)*(1 + 2*x - 2*x^2 - 6*x^3) / (1 - 3*x + x^2 - 8*x^3 + 12*x^4 - 2*x^5 + 12*x^6). - Colin Barker, Feb 25 2019
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EXAMPLE
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Some solutions for n=5:
..0..1. .1..0. .1..0. .0..1. .1..1. .1..1. .0..0. .1..0. .1..0. .1..1
..1..0. .0..1. .0..1. .1..0. .0..0. .0..0. .1..0. .0..1. .1..0. .0..1
..1..0. .0..1. .0..0. .0..0. .0..0. .0..1. .1..1. .1..0. .1..0. .0..0
..0..1. .1..0. .1..0. .0..1. .1..0. .0..1. .1..1. .0..0. .0..1. .0..0
..0..1. .0..0. .1..1. .1..1. .1..0. .0..1. .1..0. .1..1. .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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