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A189274
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Number of nX3 array permutations with each element not moved or moved diagonally or antidiagonally by one
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3
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1, 9, 45, 225, 1125, 5625, 28125, 140625, 703125, 3515625, 17578125, 87890625, 439453125, 2197265625, 10986328125, 54931640625, 274658203125, 1373291015625, 6866455078125, 34332275390625, 171661376953125, 858306884765625, 4291534423828125, 21457672119140625
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OFFSET
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1,2
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COMMENTS
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Column 3 of A189280
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..200
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FORMULA
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Empirical: a(n) = 5*a(n-1) for n>2
Apparently, the O.g.f. is x*(1+4x)/(1-5x). - Philippe Deléham, Feb 25 2012
Apparently : a(n) = Sum_{k, 1<=k<=n} A207628(n,k)*2^(k-1). - Philippe Deléham, Feb 25 2012
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EXAMPLE
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Some solutions for 4X3
..0..1..4....0..1..4....4..5..2....4..1..2....0..5..2....0..5..2....0..5..2
..3..2..5....3..2..5....3..0..1....3..0..5....3..8..1....7..4..1....3..4..1
.10.11..8....6..7..8...10.11..8....6..9.10....6.11..4...10..3..8....6..7..8
..9..6..7....9.10.11....9..6..7....7..8.11....9.10..7....9..6.11....9.10.11
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MATHEMATICA
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Join[{1}, LinearRecurrence[{5}, {9}, 70]] (* From Vladimir Joseph Stephan Orlovsky, Feb 26 2012 *)
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CROSSREFS
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Sequence in context: A024209 A179855 A180796 * A026092 A054628 A132133
Adjacent sequences: A189271 A189272 A189273 * A189275 A189276 A189277
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin Apr 19 2011
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STATUS
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approved
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