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 A087137 a(n) is the number of permutations in the symmetric group S_n that contain an odd cycle. 4
 0, 1, 1, 6, 15, 120, 495, 5040, 29295, 362880, 2735775, 39916800, 370945575, 6227020800, 68916822975, 1307674368000, 16813959537375, 355687428096000, 5214921734397375, 121645100408832000, 2004231846526284375, 51090942171709440000, 934957186489800849375 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..450 FORMULA E.g.f.: 1/(1-x)-1/sqrt(1-x^2). If n is odd then a(n) = n! else a(n) = n!-((n-1)!!)^2. MATHEMATICA CoefficientList[Series[1/(1-x)-1/Sqrt[1-x^2], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Sep 21 2014 *) PROG (PARI) x='x+O('x^33); concat(0, Vec(serlaplace(1/(1-x)-1/sqrt(1-x^2)))) \\ Michel Marcus, Sep 21 2014 CROSSREFS Cf. A059838, A001818. Sequence in context: A133472 A213873 A219771 * A056317 A129421 A013227 Adjacent sequences:  A087134 A087135 A087136 * A087138 A087139 A087140 KEYWORD nonn AUTHOR Yuval Dekel (dekelyuval(AT)hotmail.com), Oct 18 2003 EXTENSIONS Formulae and more terms from Vladeta Jovovic, Oct 31 2003 Two more terms from Michel Marcus, Sep 21 2014 STATUS approved

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Last modified August 12 04:52 EDT 2022. Contains 356067 sequences. (Running on oeis4.)