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 A038037 Number of labeled rooted compound windmills (mobiles) with n nodes. 11
 1, 2, 9, 68, 730, 10164, 173838, 3524688, 82627200, 2198295360, 65431163160, 2154106470240, 77714083773456, 3048821300491680, 129221979665461200, 5884296038166954240, 286492923374605966080, 14851359950834255500800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Camb. 1998, p. 241 (3.3.83). LINKS Alois P. Heinz, Table of n, a(n) for n = 1..140 C. G. Bower, Transforms (2) P. Flajolet and R. Sedgewick, Analytic Combinatorics, 2009; see page 454 B. R. Jones, On tree hook length formulas, Feynman rules and B-series, Master's thesis, Simon Fraser University, 2014. FORMULA Divides by n and shifts left under "CIJ" (necklace, indistinct, labeled) transform. E.g.f. A(x) satisfies A(x) = -x*log(1-A(x)). a(n) = Sum_{j=0..n} binomial(n,j)*abs(Stirling1(n-1,j))*j!, n > 0. - Vladimir Kruchinin, Feb 03 2011 a(n) ~ sqrt(-1-LambertW(-1,-exp(-2))) * (-LambertW(-1,-exp(-2)))^(n-1) * n^(n-1) / exp(n). - Vaclav Kotesovec, Dec 27 2013 E.g.f.: series reversion of x/(1 - log(1-x)). - Andrew Howroyd, Sep 19 2018 MAPLE logtr:= proc(p) local b; b:=proc(n) option remember; local k; if n=0 then 1 else p(n)- add(k *binomial(n, k) *p(n-k) *b(k), k=1..n-1)/n fi end end: b:= logtr(-a): a:= n-> `if`(n<=1, 1, -n*b(n-1)): seq(a(n), n=1..25); # Alois P. Heinz, Sep 14 2008 MATHEMATICA a[n_] = Sum[Binomial[n, j]*Abs[StirlingS1[n-1, j]]*j!, {j, 0, n}]; Array[a, 18] (* Jean-François Alcover, Jun 22 2011, after Vladimir Kruchinin *) PROG (PARI) Vec(serlaplace(serreverse(x/(1 - log(1-x + O(x^20)))))) \\ Andrew Howroyd, Sep 19 2018 CROSSREFS Cf. A029768, A032200, A055349. Sequence in context: A227457 A134200 A217066 * A138212 A134261 A120980 Adjacent sequences:  A038034 A038035 A038036 * A038038 A038039 A038040 KEYWORD nonn,eigen AUTHOR Christian G. Bower, Sep 15 1998 STATUS approved

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Last modified October 15 01:40 EDT 2019. Contains 328025 sequences. (Running on oeis4.)