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A264202
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Number of (n+1) X (2+1) arrays of permutations of 0..n*3+2 with each element having index change +-(.,.) 0,0 0,2 or 1,0.
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1
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18, 96, 605, 3600, 21853, 131712, 795906, 4804910, 29017649, 175219200, 1058090513, 6389336434, 38582627490, 232984303104, 1406895932317, 8495659825200, 51301766577821, 309790076011680, 1870693734316914
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) + 18*a(n-2) + 5*a(n-3) - 18*a(n-4) + 3*a(n-5) + a(n-6).
Empirical g.f.: x*(18 + 42*x - 7*x^2 - 33*x^3 + 7*x^4 + 2*x^5) / ((1 + x - x^2)*(1 - 4*x - 13*x^2 + 4*x^3 + x^4)). - Colin Barker, Jan 05 2019
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EXAMPLE
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Some solutions for n=4:
..2..4..0....0..1..5....2..1..0....3..1..2....0..1..2....0..1..2....0..4..2
..5..1..3....6..7..2....6..4..5....0..7..5....5..4..3....6..7..8....3..1..5
..8..7.11....3..4..8....3.10..8....8..4..6....6..7.11....3..4..5....8..7..6
..6.13.14....9.10.11...12..7..9...12.13..9....9.10..8....9.13.14...11.10..9
..9.10.12...12.13.14...14.13.11...14.10.11...12.13.14...12.10.11...12.13.14
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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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