A224437 The Wiener index of the nanostar dendrimer NS_1[n], defined pictorially in the A. R. Ashrafi et al. reference.

730, 8002, 60754, 381490, 2146930, 11252722, 56133874, 270161650, 1265842930, 5810393842, 26243850994, 117016314610, 516299391730, 2258288837362, 9805857424114, 42314967024370, 181627585561330, 775984568599282, 3301842333205234

Offset

0,1

Comments

a(1) has been checked by the direct computation of the Wiener index (using Maple).

References

A. R. Ashrafi and P. Nikzad, Kekulé index and bounds of energy for nanostar dendrimers, Digest J. of Nanomaterials and Biostructures, 4, No. 2, 2009, 383-388.

Links

Table of n, a(n) for n=0..18.

Formula

a(n) = -754 + 3768*2^n + 2880n*4^n + 1680n*2^n - 3792*4^n.

G.f.: 2(365 - 744z + 1724z^2 - 2112z^3 + 4160z^4)/((1-z)(1-2z)^2*(1-4z)^2).

Maple

a := proc (n) options operator, arrow: 754+1680*2^n*n+2880*4^n*n-3792*4^n+3768*2^n end proc: seq(a(n), n = 0 .. 18);

Crossrefs

Cf. A224438.

Sequence in context: A141806 A158397 A031732 * A259322 A085441 A098292

Adjacent sequences: A224434 A224435 A224436 * A224438 A224439 A224440

Keyword

nonn

Author

Emeric Deutsch, Apr 06 2013

Status

approved