1,2

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.

Cf. A027838, A027839, A027840.

Sequence in context: A027233 A117650 A144038 this_sequence A027683 A000829 A061825

Adjacent sequences: A027839 A027840 A027841 this_sequence A027843 A027844 A027845

nonn

N. J. A. Sloane (njas(AT)research.att.com).