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A027845 Number of subgroups of index n in fundamental group of a certain fiber space. 1
1, 15, 43, 371, 1321, 11979 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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.

LINKS

Table of n, a(n) for n=1..6.

CROSSREFS

Sequence in context: A126369 A193647 A133343 * A201810 A292018 A289669

Adjacent sequences:  A027842 A027843 A027844 * A027846 A027847 A027848

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 18 07:22 EST 2019. Contains 329252 sequences. (Running on oeis4.)