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A221883
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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, without consecutive moves in the same direction.
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1
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3, 33, 326, 3223, 31832, 314426, 3105733, 30676867, 303010527, 2992984402, 29563182686, 292010132356, 2884328060800, 28489930453209, 281409090823688, 2779616346494657, 27455641219994600, 271192906082774221
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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) = 7*a(n-1) + 27*a(n-2) + 16*a(n-3) - 18*a(n-4) - 13*a(n-5) + 5*a(n-6) + 3*a(n-7) - a(n-8).
Empirical g.f.: x*(3 + 12*x + 14*x^2 + 2*x^3 - 5*x^4 - 2*x^5 + x^6) / (1 - 7*x - 27*x^2 - 16*x^3 + 18*x^4 + 13*x^5 - 5*x^6 - 3*x^7 + x^8). - Colin Barker, Aug 11 2018
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EXAMPLE
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Some solutions for n=3:
..1..2....0..3....0..3....0..2....1..0....0..1....1..1....1..1....1..0....0..1
..0..0....0..1....0..3....0..2....1..1....2..0....0..2....1..0....3..1....3..1
..0..3....0..2....0..0....2..0....1..2....0..3....0..2....0..3....1..0....0..1
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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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