A227707 The terminal Wiener index of the dendrimer D_n defined pictorially in Fig. 1 of the Heydari et al. reference.

12, 78, 444, 2328, 11568, 55392, 258240, 1180032, 5309184, 23594496, 103812096, 452990976, 1962946560, 8455741440, 36238835712, 154618920960, 657130192896, 2783139201024, 11751031308288, 49478024822784, 207807700795392, 870813215490048, 3641582523777024, 15199648767541248

Offset

0,1

References

A. Heydari, I. Gutman, On the terminal index of thorn graphs, Kragujevac J. Sci., 32, 2010, 57-64.

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (10, -32, 32).

Formula

a(n) = 3*2^n + 9*4^n*(n+1).

G.f.: 6*(2-7*x+8*x^2)/((1-2*x)*(1-4*x)^2).

Maple

a := proc (n) options operator, arrow: 3*2^n+9*4^n*(n+1) end proc: seq(a(n), n = 0 .. 25);

Mathematica

CoefficientList[Series[6 (2 - 7 x + 8 x^2) / ((1 - 2 x) (1 - 4 x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Aug 04 2013 *)

Prog

(Magma) [3*2^n+9*4^n*(n+1): n in [0..25]]; // Vincenzo Librandi, Aug 04 2013

Crossrefs

Cf. A227708, A227709.

Sequence in context: A124863 A022577 A321949 * A189493 A199492 A200055

Adjacent sequences: A227704 A227705 A227706 * A227708 A227709 A227710

Keyword

nonn,easy

Author

Emeric Deutsch, Aug 02 2013

Status

approved