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A189644
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Number of n X 3 array permutations with each element moving zero or one space horizontally, diagonally or antidiagonally.
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1
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3, 33, 263, 2161, 17655, 144353, 1180167, 9648721, 78885143, 644942273, 5272862503, 43109407281, 352450114615, 2881530764193, 23558566731847, 192608065601041, 1574708145738583, 12874360876413313, 105257071556189543
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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) = 9*a(n-1) - 6*a(n-2) - 8*a(n-3) + 16*a(n-4).
Empirical g.f.: x*(3 + 6*x - 16*x^2 + 16*x^3) / (1 - 9*x + 6*x^2 + 8*x^3 - 16*x^4). - Colin Barker, May 02 2018
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EXAMPLE
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Some solutions for 4 X 3:
..0..1..2....1..0..2....1..0..4....4..0..2....0..2..1....0..3..4....1..0..2
..7..5..4....3..8..5....3..2..5....3..5..1....3..4..5....1..2..7....3..6..5
..6..3.10....6..9..4...10..6..7...10..6..8....7..9..8....6..5.10....7..8..4
..9..8.11....7.11.10....9..8.11....9.11..7...10..6.11....9..8.11....9.10.11
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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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