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Search: id:A130915
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| A130915 |
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Number of permutations in the symmetric group S_n in which cycle lengths are odd and greater than 1. |
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+0
3
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| 0, 0, 2, 0, 24, 40, 720, 2688, 42560, 245376, 4072320, 31672960, 569935872, 5576263680, 109492807424, 1290701905920, 27616577064960, 380852962029568, 8845627365089280, 139696582370328576
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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E.g.f.: exp(-x)*sqrt((1+x)/(1-x)) (offset 0).
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EXAMPLE
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a(3)=2 because we have (123) and (132).
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MAPLE
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g:=exp(-x)*sqrt((1+x)/(1-x)): gser:=series(g, x=0, 30): seq(factorial(n)*coeff(gser, x, n), n=1..20); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 25 2007
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CROSSREFS
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Cf. A000246, A000166.
Sequence in context: A051728 A005359 A008842 this_sequence A127067 A052607 A052602
Adjacent sequences: A130912 A130913 A130914 this_sequence A130916 A130917 A130918
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 23 2007
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 25 2007
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