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 A192021 The Wiener index of the binomial tree of order n. 1
 0, 1, 10, 68, 392, 2064, 10272, 49216, 229504, 1048832, 4719104, 20972544, 92276736, 402657280, 1744838656, 7516209152, 32212287488, 137439019008, 584115683328, 2473901424640, 10445360988160, 43980466159616, 184717955563520, 774056190148608 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS The binomial trees b(k) of order k are ordered trees defined as follows: 1. b(0) consists of a single node. 2. For k>=1, b(k) is obtained from two copies of b(k-1) by linking them in such a way that the root of one is the leftmost child of the root of the other. See the Iyer & Reddy references. REFERENCES K. Viswanathan Iyer and K. R. Udaya Kumar Reddy, Wiener index of Binomial trees and Fibonacci trees, Int'l. J. Math. Engin. with Comp., Accepted for publication, Sept. 2009. T. H. Cormen, C. E. Leiserson and R. L. Rivest: Introduction to Algorithms. MIT Press / McGraw-Hill (1990) LINKS B. E. Sagan, Y-N. Yeh and P. Zhang, The Wiener Polynomial of a Graph, Internat. J. of Quantum Chem., 60, 1996, 959-969. K. Viswanathan Iyer and K. R. Udaya Kumar Reddy, Wiener index of binomial trees and Fibonacci trees, arXiv:0910.4432 [cs.DM], 2009. Index entries for linear recurrences with constant coefficients, signature (10,-32,32). FORMULA a(n) = Sum_{k>=1} k*A192020(n,k). From Colin Barker, Jul 07 2012: (Start) a(n) = 2^(n-1)*(1+2^n*(n-1)). a(n) = 10*a(n-1) - 32*a(n-2) + 32*a(n-3). G.f.: x/((1-2*x)*(1-4*x)^2). (End) MAPLE a := proc(n) (n-1)*2^(2*n-1)+2^(n-1) end proc: seq(a(n), n = 0 .. 23); MATHEMATICA LinearRecurrence[{10, -32, 32}, {0, 1, 10}, 23] (* Jean-François Alcover, Sep 23 2017 *) CROSSREFS Cf. A192020. Sequence in context: A197751 A144052 A280438 * A026984 A104598 A026901 Adjacent sequences:  A192018 A192019 A192020 * A192022 A192023 A192024 KEYWORD nonn,easy AUTHOR Emeric Deutsch, Jun 22 2011 EXTENSIONS Initial 0 in the sample values which is Wiener index of singleton tree b(0), and consequent amendments to formulas. - Kevin Ryde, Sep 12 2019 STATUS approved

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Last modified August 12 09:31 EDT 2022. Contains 356069 sequences. (Running on oeis4.)