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A209539
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Number of nX4 array permutations with every element making zero or one right-handed knight moves (out 2, right 1)
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1
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1, 4, 72, 729, 6480, 63504, 635040, 6350400, 63504000, 635040000, 6350400000, 63504000000, 635040000000, 6350400000000, 63504000000000, 635040000000000, 6350400000000000, 63504000000000000, 635040000000000000
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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) = 10*a(n-1) for n>6
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EXAMPLE
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Some solutions for n=4
..6..7..9..3....0..8..2..3....6..7..2.10....0..7..9..3....6..1..2..3
.10..5..0..1...10.12.13.14....4.12..0..1....4..5..6..1....4.11..0.14
.14..2..4.11....1..9..4.11...14.15..3.11....8..2.10.11....8..9.10..5
.12.13..8.15....5..6..7.15....5.13..8..9...12.13.14.15...12.13..7.15
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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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