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A189429
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Number of n X 3 array permutations with each element not moving, or moving one space N, SW or SE.
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1
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1, 3, 9, 31, 109, 367, 1245, 4247, 14453, 49167, 167325, 569447, 1937829, 6594495, 22441517, 76369751, 259890293, 884421039, 3009733885, 10242290119, 34855077573, 118613751711, 403649138125, 1373640273207, 4674573594645
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = a(n-1) +4*a(n-2) +10*a(n-3) +12*a(n-4) +8*a(n-5).
Empirical g.f.: x*(1 + 2*x + 2*x^2) / (1 - x - 4*x^2 - 10*x^3 - 12*x^4 - 8*x^5). - Colin Barker, May 02 2018
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EXAMPLE
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Some solutions for 4 X 3:
..0..4..5....0..4..5....0..1..2....3..1..2....0..4..2....0..4..5....0..1..2
..6..2..1....1..2..8....3..7..5....6..0..5....1..7..5....3..2..1....3..4..5
..9..3..8....6..3.11....6.10..4....4.10.11....6..3..8....6..7..8....9.10..8
..7.10.11....9.10..7....9..8.11....9..8..7....9.10.11....9.10.11....7..6.11
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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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