A224431 The Wiener index of the dendrimer D_2[n], defined pictorially in the A. R. Ashrafi et al. reference.

224, 4878, 46250, 322146, 1914578, 10351026, 52620146, 256370418, 1211362802, 5594160114, 25382926322, 113581912050, 502582927346, 2203470381042, 9586688622578, 41438522310642, 178122308583410, 761964546228210, 3245764578377714

Offset

0,1

Comments

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

References

A. R. Ashrafi and H. Shabani, Computing Padmakar-Ivan index of four classes of dendrimers, Bulgarian Chem. Comm., 44, No. 2, 2012, 127-130.

Links

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

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

Formula

a(n) = -14+4846*2^n+1056*2^n*n+2880*4^n*n-4608*4^n.

G.f. = 2(112+983z-1414z^2-32z^3+288z^4)/[(1-z)(1-2z)^2(1-4z)^2].

Maple

a := proc (n) options operator, arrow: -14+4846*2^n+1056*2^n*n+2880*4^n*n-4608*4^n end proc: seq(a(n), n = 0 .. 18);

Crossrefs

Cf. A224432

Sequence in context: A341048 A232804 A032802 * A280858 A281604 A007771

Adjacent sequences: A224428 A224429 A224430 * A224432 A224433 A224434

Keyword

nonn,easy

Author

Emeric Deutsch, Apr 06 2013

Status

approved