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A032181
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Number of ways to partition n labeled elements into pie slices each of at least 2 elements.
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1
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0, 1, 1, 4, 11, 56, 267, 1730, 11643, 93532, 804563, 7789838, 81109107, 923080328, 11250876171, 147433014058, 2056359699659, 30514968348500, 479058943716579, 7942752339181286, 138576460230586755, 2539126631897727808, 48733588613803358939
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OFFSET
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1,4
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LINKS
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FORMULA
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"CIJ" (necklace, indistinct, labeled) transform of 0, 1, 1, 1...
E.g.f.: A(x) = log(1/(2+x-exp(x))).
a(n) = n! * sum(k=1..n, sum(j=0..k, binomial(k,j) *stirling2(n-k+j,j) *j!/(n-k+j)! *(-1)^(k-j))/k). - Vladimir Kruchinin, Feb 01 2011
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MATHEMATICA
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Rest[CoefficientList[Series[Log[1/(2+x-E^x)], {x, 0, 20}], x]* Range[0, 20]!] (* Vaclav Kotesovec, Sep 30 2013 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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