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 A122681 Sum of the Wiener indices of all trees having n vertices. 2
 0, 1, 4, 19, 54, 180, 508, 1533, 4332, 13041, 37492, 111367, 326636, 968802, 2858460, 8483290, 25113618, 74512947, 220885446, 655274837, 1943117294, 5763235194, 17089323366, 50673594159, 150232437482, 445359235627, 1320070201468 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS C program, see the first Bomfim link, around the function Gen() of Gang Li & Frank Ruskey. - Washington Bomfim, Feb 23 2011 LINKS W. Bomfim, C program Stephan Wagner, Graph-theoretical enumeration and digital expansions: an analytic approach, Dissertation, Fakult. f. Tech. Math. u. Tech. Physik, Tech. Univ. Graz, Austria, Feb. 2006, page 31 Stephan Wagner, On the average Wiener index of degree-restricted trees, Australas. J. Combinat. 37 (2007) 187, Table 2 EXAMPLE a(4)=19; indeed, there are 2 trees on 4 vertices: the path abcd with Wiener index 1+1+1+2+2+3=10 and the star tree on 4 vertices with Wiener index 1+1+1+2+2+2 = 9. - Emeric Deutsch, Feb 20 2016 CROSSREFS Cf. A000055. Sequence in context: A253008 A186310 A122684 * A215862 A174612 A020496 Adjacent sequences:  A122678 A122679 A122680 * A122682 A122683 A122684 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 23 2006 EXTENSIONS a(11)-a(27) from Washington Bomfim, Feb 23 2011 Name edited by Emeric Deutsch, Feb 20 2016 STATUS approved

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Last modified February 29 05:25 EST 2020. Contains 332353 sequences. (Running on oeis4.)