A221014 The Wiener index of the dendrimer G_n , defined pictorially in the Ashrafi - Shabani - Diudea reference.

666, 10854, 91062, 586278, 3293478, 17076582, 84106854, 399946086, 1854359910, 8436473190, 37822942566, 167600700774, 735637781862, 3203485138278, 13857655946598, 59605426371942, 255120762469734, 1087278900313446, 4616298106453350, 19533920370425190

Offset

1,1

Links

Table of n, a(n) for n=1..20.

A. R. Ashrafi, H. Shabani, M. V. Diudea, Balaban index of dendrimers, MATCH, Commun. Math. Comput. Chem. 69, 2013, 151-158.

Index entries for linear recurrences with constant coefficients, signature (13,-64,148,-160,64)

Formula

a(n) = -666 +2^n*(-270*n+2340) +4^n*(972*n-1674).

G.f.: 18*x*(37+122*x-412*x^2-80*x^3)/((1-x)*(1-2*x)^2*(1-4*x)^2). - Bruno Berselli, Dec 30 2012

Maple

a := proc (n) options operator, arrow: -666+2^n*(-270*n+2340)+4^n*(972*n-1674) end proc: seq(a(n), n = 1 .. 20);

Crossrefs

Cf. A221015.

Sequence in context: A051003 A183655 A104181 * A057564 A227490 A171114

Adjacent sequences: A221011 A221012 A221013 * A221015 A221016 A221017

Keyword

nonn,easy

Author

Emeric Deutsch, Dec 29 2012

Status

approved