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A169771
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Number of open knight's tour diagrams of a 3 X n chessboard that have "type F": the endpoints occur in different columns and agree in color with the cells in the nearest corner.
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2
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2, 0, 0, 52, 224, 520, 1616, 10320, 37024, 125120, 441200, 1798576, 6327472, 22985504, 81178008, 301420176, 1057619944, 3818476576, 13412523392, 48285742208, 168992600680, 602349395456, 2106360581920, 7471875943776, 26073917403304, 92017860990176, 320713651212384
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listen;
history;
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OFFSET
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4,1
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REFERENCES
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D. E. Knuth, Long and skinny knight's tours, in Selected Papers on Fun and Games, to appear, 2010.
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LINKS
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Seiichi Manyama, Table of n, a(n) for n = 4..1000
George Jelliss, Open knight's tours of three-rank boards, Knight's Tour Notes, note 3a (21 October 2000).
George Jelliss, Closed knight's tours of three-rank boards, Knight's Tour Notes, note 3b (21 October 2000).
D. E. Knuth Generating functions for A169770-A169777 and A169696.
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FORMULA
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Asymptotic value: 0.02789*3.45059^n.
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CROSSREFS
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Cf. A070030, A169696, A169764-A169777.
Sequence in context: A013369 A013416 A156433 * A326779 A293140 A008551
Adjacent sequences: A169768 A169769 A169770 * A169772 A169773 A169774
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, May 10 2010, based on a communication from Don Knuth, Apr 28 2010
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STATUS
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approved
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