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A221162
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Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor.
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1
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3, 33, 352, 3721, 39254, 413908, 4363921, 46008619, 485064009, 5113971944, 53915979657, 568429529006, 5992882377940, 63182219138721, 666122336505939, 7022845559348401, 74040993741513520, 780605056433123273
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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) = 13*a(n-1) - 26*a(n-2) + a(n-3).
Empirical g.f.: x*(3 - 6*x + x^2) / (1 - 13*x + 26*x^2 - x^3). - Colin Barker, Aug 04 2018
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EXAMPLE
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Some solutions for n=3:
..0..0....3..1....1..0....0..0....0..0....2..0....1..0....0..2....3..1....0..3
..3..0....0..1....2..2....2..1....3..1....2..1....0..3....0..0....0..0....1..1
..2..1....0..1....1..0....3..0....1..1....1..0....2..0....4..0....2..0....1..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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