A175855 The number of closed Knight's tours on a 5 X 2n board.

0, 0, 8, 44202, 13311268, 4557702762, 1495135512514, 491857035772330, 161514101568508400, 53034853662012222798, 17414154188157170439208, 5717847862749642677204182, 1877435447920358266870897874, 616447390029326136628439042672, 202407848349722353779265745190616, 66459727085467788423206394162537418, 21821760546806761707309514948565417796, 7165079447164571822068029945303172129766, 2352622444655438705806553391345493395131580, 772473271844923268504474277422663237674924998

Offset: 1

Author

Johan de Ruiter, Dec 05 2010

Keywords

• nonn

Examples

			The smallest 5 X 2n board admitting a closed Knight's tour is the 5 X 6, on which there are 8 such tours.
		

Links

• J. de Ruiter, Counting Domino Coverings and Chessboard Cycles, 2010.

Crossrefs

A070030 deals with 3 X 2n boards, A175881 deals with 6 X n boards.

Cf. A383661.

Formula

a(n) = A383661(5n). - Don Knuth, May 05 2025