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 A169771 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. 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,1 REFERENCES D. E. Knuth, Long and skinny knight's tours, in Selected Papers on Fun and Games, to appear, 2010. LINKS 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). FORMULA Asymptotic value: 0.02789*3.45059^n. CROSSREFS Cf. A070030, A169696, A169764-A169777. Sequence in context: A013369 A013416 A156433 * A293140 A008551 A183896 Adjacent sequences:  A169768 A169769 A169770 * A169772 A169773 A169774 KEYWORD nonn AUTHOR N. J. A. Sloane, May 10 2010, based on a communication from Don Knuth, Apr 28 2010 STATUS approved

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Last modified December 13 20:06 EST 2018. Contains 318087 sequences. (Running on oeis4.)