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 A212809 Decimal expansion of radius of convergence of g.f. for unlabeled trees (A000055). 1
 3, 3, 8, 3, 2, 1, 8, 5, 6, 8, 9, 9, 2, 0, 7, 6, 9, 5, 1, 9, 6, 1, 1, 2, 6, 2, 5, 7, 1, 7, 0, 1, 7, 0, 5, 3, 1, 8, 3, 7, 7, 4, 6, 0, 7, 5, 3, 2, 9, 6, 7, 7, 9, 5, 5, 7, 2, 3, 0, 3, 7, 7, 6, 2, 5, 7, 6, 6, 6, 0, 5, 0, 1, 8, 9, 6, 2, 0, 7, 6, 6, 5, 6, 3, 5, 2, 8, 7, 9, 8, 3, 6, 7, 3 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS M. Drmota, B. Gittenberger, The shape of unlabeled rooted random trees, Eur. J. Comb. 31 (2010) no 8, 2028-2063 E. M. Palmer and A. J. Schwenk, On the number of trees in a random forest, J. Combin. Theory, B 27 (1979), 109-121. FORMULA Equals 1/A051491. - Vaclav Kotesovec, Jul 29 2013 EXAMPLE 0.338321856899208... MATHEMATICA digits = 95; max = 200; s[n_, k_] := s[n, k] = a[n + 1 - k] + If[n < 2*k, 0, s[n - k, k]]; a[1] = 1; a[n_] := a[n] = Sum[a[k]*s[n - 1, k]*k, {k, 1, n - 1}]/(n - 1); A[x_] := Sum[a[k]*x^k, {k, 0, max}]; eq = Log[c] == 1 + Sum[A[c^-k]/k, {k, 2, max}]; r = 1/c /. FindRoot[eq, {c, 3}, WorkingPrecision -> digits + 5]; RealDigits[r, 10, digits] // First (* Jean-François Alcover, Aug 10 2016 *) CROSSREFS Cf. A000055. Sequence in context: A154178 A276800 A332684 * A294643 A029614 A143615 Adjacent sequences:  A212806 A212807 A212808 * A212810 A212811 A212812 KEYWORD nonn,cons AUTHOR N. J. A. Sloane, May 29 2012 EXTENSIONS More terms from Vaclav Kotesovec, Jul 29 2013 STATUS approved

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Last modified February 23 11:52 EST 2020. Contains 332159 sequences. (Running on oeis4.)