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A057008
Number of conjugacy classes of subgroups of index n in free group of rank 5.
1
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
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
Inverse Euler transform of A160447.
Sequence in context: A289473 A069406 A234115 * A159487 A130661 A187701
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