This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A032181 Number of ways to partition n labeled elements into pie slices each of at least 2 elements. 0
 0, 1, 1, 4, 11, 56, 267, 1730, 11643, 93532, 804563, 7789838, 81109107, 923080328, 11250876171, 147433014058, 2056359699659, 30514968348500, 479058943716579, 7942752339181286, 138576460230586755, 2539126631897727808, 48733588613803358939 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS C. G. Bower, Transforms (2) S. Giraudo, Combinatorial operads from monoids, arXiv preprint arXiv:1306.6938, 2013 Vladimir Kruchinin, D. V. Kruchinin, Composita and their properties , arXiv:1103.2582 [math.CO], 2011-2013. FORMULA "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 a(n) ~ (n-1)! / (-LambertW(-1,-exp(-2))-2)^n. - Vaclav Kotesovec, Sep 30 2013 MATHEMATICA Rest[CoefficientList[Series[Log[1/(2+x-E^x)], {x, 0, 20}], x]* Range[0, 20]!] (* Vaclav Kotesovec, Sep 30 2013 *) CROSSREFS Sequence in context: A262006 A209110 A282742 * A203577 A081073 A245545 Adjacent sequences:  A032178 A032179 A032180 * A032182 A032183 A032184 KEYWORD nonn AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 17 22:44 EST 2019. Contains 319251 sequences. (Running on oeis4.)