|
| |
|
|
A113948
|
|
Number of non-equivalent (2n+1)-fold branched coverings of the Klein bottle with one cyclic branch point.
|
|
2
| |
|
|
1, 5, 44, 1266, 72636, 6652810, 889574412, 163459302788, 39520825344016, 12164510040883218, 4644631106520877974, 2154334728240414720022, 1193170003333152768100020, 777776389315596583864343748
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
COMMENTS
| No such covering of even multiplicity exists.
|
|
|
REFERENCES
| J. H. Kwak, A. Mednykh and V. Liskovets, Enumeration of branched coverings of nonorientable surfaces with cyclic branch points, SIAM J. Discrete Math., Vol. 19, No. 2 (2005), 388-398.
|
|
|
FORMULA
| a(n)=2*sum_{k|(2n+1)}k!*((2n+1)/k)^(k-1)*phi((2n+1)/k)/(k+1) where phi(n) is the Euler function A000010.
|
|
|
CROSSREFS
| Cf. A113947, A113950.
Sequence in context: A201923 A048940 A058792 * A096763 A003185 A201876
Adjacent sequences: A113945 A113946 A113947 * A113949 A113950 A113951
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Valery A. Liskovets (liskov(AT)im.bas-net.by), Nov 10 2005
|
| |
|
|
