OFFSET
0,1
COMMENTS
a(n) is the number of edges in the nanostar dendrimer G(n), defined pictorially in the Darafsheh et al. reference (see Fig. 1, where G(2) is shown).
REFERENCES
M. R. Darafsheh, M. H. Khalifeh, Calculation of the Wiener, Szeged, and PI indices of a certain nanostar dendrimer, Ars Comb., 100, 2011, 289-298.
LINKS
Muniru A Asiru, Table of n, a(n) for n = 0..700
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
From Colin Barker, May 28 2018: (Start)
G.f.: (13 + 2*x) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>1.
(End)
MAPLE
seq(28*2^n-15, n = 0..40);
MATHEMATICA
28*2^Range[0, 40]-15 (* or *) LinearRecurrence[{3, -2}, {13, 41}, 40] (* Harvey P. Dale, Dec 02 2018 *)
PROG
(PARI) Vec((13 + 2*x) / ((1 - x)*(1 - 2*x)) + O(x^50)) \\ Colin Barker, May 28 2018
(GAP) List([0..40], n->28*2^n-15); # Muniru A Asiru, May 28 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, May 28 2018
STATUS
approved