A027842 Number of subgroups of index n in fundamental group of a certain fiber space.

1, 7, 34, 227, 1296, 10576, 77554, 729379, 7013419, 77371042, 910455096, 11877617828, 165087132666, 2480783846184, 39677415301224, 675818886754115, 12180498014887816, 231893906693650507, 4645789707491981892, 97740610362119850762, 2153888078209948673032

Offset

1,2

Links

Table of n, a(n) for n=1..21.

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.

Crossrefs

Cf. A027838, A027839, A027840, A060240.

Sequence in context: A365474 A273221 A144038 * A232043 A360506 A027683

Adjacent sequences: A027839 A027840 A027841 * A027843 A027844 A027845

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from Sean A. Irvine, Dec 07 2019

Status

approved