A123936 a(n) = A079137(n)/2.

0, 0, 4, 0, 41, 372, 3189, 15544, 94844, 606556, 3341926, 18243164, 100641235, 541792652, 2853058729, 14909615644, 77215251362, 395393899688, 2007472847598, 10120652405244, 50668068245114, 252048156500636, 1246766824001246, 6135236528242698, 30045694433419662

Offset: 1

Author

N. J. A. Sloane, Oct 30 2006

Keywords

• nonn

Comments

Number of nonequivalent (or geometrically distinct) directed open knight's tours on a 4 X n chessboard up to rotation and reflection. See A328341 for the number of geometrically distinct undirected open knights's tours. - Andrew Howroyd, Oct 12 2019

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A079137, A123935, A328341.

Extensions

Terms a(22) and beyond from Andrew Howroyd, Oct 13 2019