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A027617
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Number of permutations of n elements containing a 3-cycle.
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2
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0, 0, 0, 2, 8, 40, 200, 1400, 11200, 103040, 1030400, 11334400, 135766400, 1764963200, 24709484800, 370687116800, 5930993868800, 100826895769600, 1814871926067200, 34482566595276800, 689651331905536000, 14482682605174784000, 318619017313845248000
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OFFSET
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0,4
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..200
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FORMULA
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n! * { 1 - sum[ k=0..floor(n/3) ] (-1)^k / (3^k * k!) }.
E.g.f.: 1/(1-x) - exp(-x^3/3)/(1-x). - Geoffrey Critzer, Jan 23 2013
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MATHEMATICA
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nn=20; Range[0, nn]!CoefficientList[Series[1/(1-x)-Exp[-x^3/3]/(1-x), {x, 0, nn}], x] (* Geoffrey Critzer, Jan 23 2013 *)
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CROSSREFS
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Sequence in context: A221587 A186947 A071007 * A187071 A154626 A003305
Adjacent sequences: A027614 A027615 A027616 * A027618 A027619 A027620
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KEYWORD
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nonn
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AUTHOR
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Joe Keane (jgk(AT)jgk.org)
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EXTENSIONS
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More terms from Geoffrey Critzer, Jan 23 2013
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STATUS
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approved
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