1,2

A formula in terms of irreducible characters of the symmetric group.

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.

A. D. Mednykh, On the number of subgroups in the fundamental group of a closed surface. Commun. in Algebra, 16, No 10 (1988), 2137-2148.

Cf. A003319, A027837, A049290-A049295.

Sequence in context: A130004 A139162 A078961 this_sequence A069406 A057008 A159487

Adjacent sequences: A049289 A049290 A049291 this_sequence A049293 A049294 A049295

nonn,nice

V. A. Liskovets (liskov(AT)im.bas-net.by)