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Search: id:A066318
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| A066318 |
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Number of necklaces with n labeled beads of 2 colors. |
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+0
3
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| 2, 4, 16, 96, 768, 7680, 92160, 1290240, 20643840, 371589120, 7431782400, 163499212800, 3923981107200, 102023508787200, 2856658246041600, 85699747381248000, 2742391916199936000, 93241325150797824000
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, pg 66 (2.1.27,29).
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LINKS
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Alexsandar Petojevic, The Function vM_m(s; a; z) and Some Well-Known Sequences, Journal of Integer Sequences, Vol. 5 (2002), Article 02.1.7
Index entries for sequences related to necklaces
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FORMULA
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a(n)=(n-1)!*2^n. E.g.f.: log(1/(1-2x)).
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MAPLE
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seq(count(Permutation(n))*count(Subset(n+1)), n=0..17); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 16 2006
with(combstruct):A:=[N, {N=Cycle(Union(Z$2))}, labeled]: seq(count(A, size=n), n=1..18); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 07 2007
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CROSSREFS
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Apart from initial term, same as A032184.
Sequence in context: A009565 A009838 A088335 this_sequence A135249 A110365 A047892
Adjacent sequences: A066315 A066316 A066317 this_sequence A066319 A066320 A066321
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KEYWORD
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nonn
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AUTHOR
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Christian G. Bower (bowerc(AT)usa.net), Dec 13 2001
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