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A221223
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Number of n X 2 arrays of occupancy after each element stays put or moves to some king-move neighbor.
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1
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3, 35, 400, 4525, 51025, 574800, 6473175, 72891475, 820773600, 9242002325, 104065684825, 1171786908400, 13194399201775, 148569807813675, 1672905820612800, 18837029565221725, 212106191270112225
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 15*a(n-1) - 43*a(n-2) + 10*a(n-3).
Empirical g.f.: x*(3 - 10*x + 4*x^2) / (1 - 15*x + 43*x^2 - 10*x^3). - Colin Barker, Aug 04 2018
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EXAMPLE
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Some solutions for n=3:
..0..0....2..0....2..1....2..0....1..3....0..0....3..1....0..0....2..1....2..0
..4..0....2..1....0..0....2..0....0..0....1..2....1..1....5..1....0..1....0..2
..0..2....1..0....1..2....1..1....0..2....3..0....0..0....0..0....2..0....2..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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