A027845 Number of subgroups of index n in fundamental group of a certain fiber space.

1, 15, 43, 371, 1321, 11979

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

References

• V. A. Liskovets and A. Mednykh, Enumeration of subgroups in the fundamental groups of orientable circle bundles over surfaces, Commun. in Algebra, 28, No. 4 (2000), 1717-1738.