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A039745
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Diameter of symmetric group S_n when generated by (1,2) and (1,2,3,...,n).
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3
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0, 1, 2, 6, 11, 18, 25, 35, 45, 58, 71
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| a(n) is smallest number such that every element of S_n can be written as a product of at most a(n) terms each of which is the transposition (1,2) or the n-cycle (1,2,3,...,n).
Comment from Max Alekseyev, Sep 09 2011: The distinction between A039745 and A186783 comes from whether we treat the Cayley graph of the generating set as directed or undirected (alternatively, whether we allow multiplication by inverses of generators when constructing elements). A039745 deals with the directed Cayley graph, while A186783 deals with the undirected one.
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EXAMPLE
| a(3)=2 because (1,3,2) = (1,2,3)(1,2)
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PROG
| (Other) (SAGE) def a(n): return PermutationGroup([[(1, 2)], [tuple(1..n)]]).cayley_graph().diameter() [From Max Alekseyev (maxale(AT)gmail.com), Mar 02 2010]
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CROSSREFS
| See A186783 for another version.
Sequence in context: A081689 A176708 A104813 * A037258 A201993 A024521
Adjacent sequences: A039742 A039743 A039744 * A039746 A039747 A039748
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KEYWORD
| hard,nonn,nice,more,changed
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AUTHOR
| David desJardins (desj(AT)idaccr.org)
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