A227488 The Wiener index of the nanostar dendrimer NSC_5C_6[n], defined pictorially in the Ashrafi et al. and the Rostami et al. references.

2192, 75884, 811076, 5876276, 35361428, 191654996, 973156820, 4730314964, 22295250644, 102723642068, 465158748884, 2077879380692, 9180871101140, 40201652095700, 174720788384468, 754542896859860, 3240816616917716

Offset

1,1

Comments

a(2) has been checked by the direct computation of the Wiener index (using Maple).

Links

Table of n, a(n) for n=1..17.

A. R. Ashrafi and P. Nikzad, Szeged index of nanostar dendrimers, Digest J. of Nanomaterials and Biostructures, 4, No. 1, 2009, 155-157.

M. Rostami, M. Shabanian, and H. Moghanian, Some topological indices for theoretical study of two types of nanostar dendrimers, Digest J. of Nanomaterials and Biostructures, 7, No. 1, 2012, 247-252.

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

Formula

a(n) = -13612 + 2^n*(72*n + 45270) + 4^n*(12960*n - 31680).

G.f. = 4*z*(548 + 11847*z -8782*z^2 - 33888*z^3 - 352*z^4)/((1-z)*(1-2*z)^2*(1-4*z)^2).

Maple

a := proc (n) options operator, arrow: -13612+2^n*(72*n+45270)+4^n*(12960*n-31680) end proc: seq(a(n), n = 1 .. 20);

Crossrefs

Cf. A227489

Sequence in context: A251316 A320718 A134158 * A225719 A352344 A342428

Adjacent sequences: A227485 A227486 A227487 * A227489 A227490 A227491

Keyword

nonn,easy

Author

Emeric Deutsch, Jul 16 2013

Status

approved