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A160446 Number of isomorphism classes of n-fold coverings of a connected graph with Betti number 4. 3
1, 16, 251, 14491, 1730861, 373486525, 128038522439, 65551419139302, 47785761199635528, 47785253957386480534, 63601854214623350663136, 109903723926415382728069729, 241458148813601665905147070195 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Number of orbits of the conjugacy action of Sym(n) on Sym(n)^4 [Kwak and Lee, 2001]. - Álvar Ibeas, Mar 24 2015
REFERENCES
J. H. Kwak and J. Lee, Enumeration of graph coverings, surface branched coverings and related group theory, in Combinatorial and Computational Mathematics (Pohang, 2000), ed. S. Hong et al., World Scientific, Singapore 2001, pp. 97-161.
LINKS
J. H. Kwak and J. Lee, Isomorphism classes of graph bundles. Can. J. Math., 42(4), 1990, pp. 747-761.
PROG
(Sage) [sum(p.aut()**3 for p in Partitions(n)) for n in range(1, 9)] # Álvar Ibeas, Mar 24 2015
CROSSREFS
Fifth column of A160449.
Sequence in context: A282312 A110394 A220459 * A317894 A228982 A158531
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 12 2009
EXTENSIONS
Name clarified and more terms added by Álvar Ibeas, Mar 24 2015
STATUS
approved

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Last modified March 29 02:16 EDT 2024. Contains 371264 sequences. (Running on oeis4.)