OFFSET
0,1
COMMENTS
a(n) (n>=0) is the number of edges of the dendrimer graph K[n], defined pictorially in the Ghorbani et al. reference (see Figs. 9, 10, and 11).
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
M. Ghorbani, K. Malekjani, and A. Khaki, Eccentric connectivity index of some dendrimer graphs, Iranian J. of Math. Chemistry, 3, Supplement 1 (2012), 7-18.
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
From Colin Barker, May 25 2018: (Start)
G.f.: 2*(17 - 24*x) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>1.
(End)
MAPLE
seq(20*2^n+14, n = 0 .. 40);
MATHEMATICA
20*2^Range[0, 40]+14 (* or *) LinearRecurrence[{3, -2}, {34, 54}, 40] (* Harvey P. Dale, Sep 16 2021 *)
PROG
(PARI) Vec(2*(17 - 24*x) / ((1 - x)*(1 - 2*x)) + O(x^40)) \\ Colin Barker, May 25 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, May 24 2018
STATUS
approved