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A297972
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Number of n X 2 0..1 arrays with every element equal to 2, 3, 4 or 5 king-move adjacent elements, with upper left element zero.
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8
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0, 1, 3, 6, 17, 41, 104, 261, 655, 1646, 4133, 10381, 26072, 65481, 164459, 413046, 1037385, 2605441, 6543688, 16434781, 41276727, 103668446, 260368189, 653926981, 1642368440, 4124885761, 10359845043, 26019239206, 65348545857, 164125953561
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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) = a(n-1) + 3*a(n-2) + 2*a(n-3).
Empirical g.f.: x^2*(1 + 2*x) / (1 - x - 3*x^2 - 2*x^3). - Colin Barker, Feb 19 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
..0..0. .0..0. .0..0. .1..0. .0..1. .0..0. .0..0. .0..0. .0..0. .0..0
..1..1. .0..0. .0..0. .1..1. .1..1. .1..1. .1..0. .0..0. .0..0. .1..1
..1..0. .0..0. .0..1. .0..0. .1..0. .1..1. .1..1. .1..0. .0..1. .1..1
..0..0. .1..0. .1..1. .0..0. .0..0. .1..1. .1..1. .1..1. .1..1. .1..0
..1..1. .1..1. .0..0. .1..0. .1..0. .1..1. .1..0. .0..0. .1..0. .0..0
..1..1. .1..1. .0..0. .1..1. .1..1. .1..1. .0..0. .0..0. .0..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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