A057008 Number of conjugacy classes of subgroups of index n in free group of rank 5.

1, 31, 1361, 334576, 207009649, 268530771271, 644969015852641, 2642258726261312896, 17337468317813249073281, 173383832437017181584973783, 2538593496477071922439308897841, 52641334467700181691498204296713016, 1503509056221581488501100896035227575441

Offset

1,2

References

R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.13(c), pp. 76, 112.

Links

Table of n, a(n) for n=1..13.

J. H. Kwak and J. Lee, Enumeration of connected graph coverings, J. Graph Th., 23 (1996), 105-109.

J. H. Kwak and J. Lee, Enumeration of graph coverings and surface branched coverings, Lecture Note Series 1 (2001), Com^2MaC-KOSEF, Korea. See chapter 3.

V. A. Liskovets, Reductive enumeration under mutually orthogonal group actions, Acta Applic. Math., 52 (1998), 91-120.

Crossrefs

Cf. A057004-A057013.

Inverse Euler transform of A160447.

Sequence in context: A289473 A069406 A234115 * A159487 A130661 A187701

Adjacent sequences: A057005 A057006 A057007 * A057009 A057010 A057011

Keyword

nonn

Author

N. J. A. Sloane, Sep 09 2000

Extensions

More terms from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 25 2001

Status

approved