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A264185
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Number of (n+1) X (3+1) arrays of permutations of 0..n*4+3 with each element having index change +-(.,.) 0,0 1,-1 or 2,2.
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1
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8, 81, 720, 7056, 70560, 705600, 7056000, 70560000, 705600000, 7056000000, 70560000000, 705600000000, 7056000000000, 70560000000000, 705600000000000, 7056000000000000, 70560000000000000, 705600000000000000
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OFFSET
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1,1
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 10*a(n-1) for n>4.
Conjectures from Colin Barker, Jan 05 2019: (Start)
G.f.: x*(8 + x - 90*x^2 - 144*x^3) / (1 - 10*x).
a(n) = 441*2^n * 5^(n-4) for n>3.
(End)
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EXAMPLE
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Some solutions for n=4:
..0.11..2..6...10.11..2..3....0.11..2..6....0..1..2..6...10..4..2..3
..1..5..3..7....4..8..6..7....1..5..3..7....4.15..3.10....1.15..6..7
.18..9.10.14...18.12..0..1....8.19.13.14....5.19..7.11...18..9..0.11
.12.16..4.15....9.16.14..5...12.10..4.18...12.13.17.18...12.13.17..5
.13.17..8.19...13.17.15.19...16.17.15..9...16.14..8..9...16.14..8.19
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CROSSREFS
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Column 3 of A264190.
Sequence in context: A240632 A007792 A301837 * A302065 A098308 A055996
Adjacent sequences: A264182 A264183 A264184 * A264186 A264187 A264188
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Nov 06 2015
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STATUS
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approved
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