1,2
See reference for more information.
I. P. Goulden, J. H. Kwak and J. Lee, Enumerating branched orientable surface coverings over a non-orientable surface, Discr. Math. 303 (2005), 42-55.
Table of n, a(n) for n=1..5.
Sequence in context: A170720 A170758 A218741 * A009983 A269028 A158768
Adjacent sequences: A112614 A112615 A112616 * A112618 A112619 A112620
nonn
N. J. A. Sloane, Dec 23 2005
approved
