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A221196
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Number of n X 3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with no occupancy greater than 2.
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1
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2, 10, 46, 212, 976, 4492, 20672, 95128, 437752, 2014400, 9269632, 42655888, 196288736, 903257824, 4156502752, 19126892096, 88015820416, 405020564416, 1863774679808, 8576493051520, 39466269101440, 181611106939904
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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) = 6*a(n-1) - 6*a(n-2) - 2*a(n-3).
Empirical g.f.: 2*x*(1 - x - x^2) / (1 - 6*x + 6*x^2 + 2*x^3). - Colin Barker, Aug 04 2018
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EXAMPLE
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Some solutions for n=3:
..0..2..0....0..2..0....1..2..0....1..2..1....1..2..1....1..2..0....0..2..1
..1..2..2....0..2..2....0..2..1....1..2..0....0..2..1....1..2..0....0..2..2
..0..2..0....0..2..1....0..2..1....0..2..0....0..2..0....0..2..1....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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