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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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2
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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; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| E.g.f.: exp(-x)*sqrt((1+x)/(1-x)) (offset 0).
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EXAMPLE
| a(3)=2 because we have (123) and (132).
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MAPLE
| 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
| Cf. A000246, A000166.
Sequence in context: A201954 A005359 A008842 * A127067 A052607 A052602
Adjacent sequences: A130912 A130913 A130914 * A130916 A130917 A130918
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 23 2007
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 25 2007
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