A169777 Number of geometrically distinct open knight's tours of a 3 X n chessboard.

3, 0, 0, 14, 104, 146, 773, 2698, 14350, 32296, 161714, 460022, 2159794, 5851548, 26468357, 76442996, 330719293, 965759972, 4056479056, 12186078360, 49668414086, 151760518296, 604396415979, 1879966906486, 7330203447133, 23126786408904, 88609897281582

Offset: 4

Author

N. J. A. Sloane, May 10 2010, based on a communication from Don Knuth, Apr 28 2010

Keywords

• nonn

Examples

			The three distinct 3x4 tours were published by Euler in Memoires Acad. Roy. Sci. (Berlin, 1759), 310-337.
		

References

• D. E. Knuth, Long and skinny knight's tours, in Selected Papers on Fun and Games, to appear, 2010.

Links

• 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.

Crossrefs

Cf. A070030, A169696, A169764-A169777.

Formula

a(n) = A169696(n)/4 + A169776(n)/2.