OFFSET
1,1
REFERENCES
R.Balakrishnan, K.Viswanathan Iyer, K.T.Raghavendra, "Wiener index of two special trees", MATCH Commun. Math. Comput. Chem., 57(2), 2007, 385-392.
LINKS
Index entries for linear recurrences with constant coefficients, signature (12,-52,96,-64).
FORMULA
a(n) = (n+4)2^(n+1) + (n-2)2^(2n+2), n>0.
G.f.: 4*x / ( (4*x-1)^2*(2*x-1)^2 ). [From R. J. Mathar, Sep 15 2010]
EXAMPLE
For n=1, the complete binary tree with level 1 is P_{3} whose Wiener index is 4.
MATHEMATICA
LinearRecurrence[{12, -52, 96, -64}, {4, 48, 368, 2304}, 40] (* Harvey P. Dale, Nov 05 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
K.V.Iyer, Mar 24 2009
STATUS
approved