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A264508
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Number of (2+1)X(n+1) arrays of permutations of 0..n*3+2 with each element having directed index change -1,1 0,-1 0,1 or 1,0.
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1
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2, 2, 14, 38, 137, 432, 1417, 4554, 14710, 47394, 152762, 492284, 1586369, 5112128, 16473473, 53085636, 171065674, 551254626, 1776394534, 5724372546, 18446568521, 59443412528, 191554172489, 617276369198, 1989150291038, 6409964077506
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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) = 2*a(n-1) +7*a(n-2) -8*a(n-3) -9*a(n-4) +10*a(n-5) -a(n-6) +a(n-8) -10*a(n-9) +9*a(n-10) +8*a(n-11) -7*a(n-12) -2*a(n-13) +a(n-14)
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EXAMPLE
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Some solutions for n=4
..1..0..3..4..8....1..2..3..7..8....1..2..6..4..3....1..2..6..4..3
..6.10..2..7.13....0.10.11.12..4....0..7.11.12..8....0..7..8.12.13
..5.12.11.14..9....5..6.13.14..9....5.10.13.14..9....5.10.11.14..9
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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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