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Search: id:A001869
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| A001869 |
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Number of n-bead necklaces with 5 colors.
(Formerly M3860 N1582)
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+0
7
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| 1, 5, 15, 45, 165, 629, 2635, 11165, 48915, 217045, 976887, 4438925, 20346485, 93900245, 435970995, 2034505661, 9536767665, 44878791365, 211927736135, 1003867701485, 4768372070757, 22706531350485, 108372083629275, 518301258916445
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
E. N. Gilbert and J. Riordan, Symmetry types of periodic sequences, Illinois J. Math., 5 (1961), 657-665.
J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 162.
R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 7.112(a).
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..200
Index entries for sequences related to necklaces
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 5
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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(1/n)*Sum_{d|n} phi(d)*4^(n/d), n>0.
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CROSSREFS
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Adjacent sequences: A001866 A001867 A001868 this_sequence A001870 A001871 A001872
Sequence in context: A084244 A099235 A035069 this_sequence A058425 A079798 A037504
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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