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 A005173 Number of trees of subsets of an n-set. (Formerly M4844) 1
 0, 1, 12, 61, 240, 841, 2772, 8821, 27480, 84481, 257532, 780781, 2358720, 7108921, 21392292, 64307941, 193185960, 580082161, 1741295052, 5225982301, 15682141200, 47054812201, 141181213812, 423577195861, 1270798696440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES F. R. McMorris and T. Zaslavsky, The number of cladistic characters, Math. Biosciences, 54 (1981), 3-10. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS F. R. McMorris and T. Zaslavsky, The number of cladistic characters, Math. Biosciences, 54 (1981), 3-10. [Annotated scanned copy] Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992. Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992 FORMULA G.f.: x ( 1 + 6 x ) / ( 1 - x ) ( 1 - 2 x ) ( 1 - 3 x ). First differences give A003063, 3^(n-1)-2^n. MAPLE A005173:=-z*(1+6*z)/(z-1)/(3*z-1)/(2*z-1); [Conjectured by Simon Plouffe in his 1992 dissertation.] CROSSREFS Sequence in context: A240002 A114241 A127766 * A196144 A294682 A177677 Adjacent sequences:  A005170 A005171 A005172 * A005174 A005175 A005176 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Larry Reeves (larryr(AT)acm.org), Feb 06 2001 STATUS approved

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Last modified April 13 17:30 EDT 2021. Contains 342936 sequences. (Running on oeis4.)