login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A224431 The Wiener index of the dendrimer D_2[n], defined pictorially in the A. R. Ashrafi et al. reference. 1
224, 4878, 46250, 322146, 1914578, 10351026, 52620146, 256370418, 1211362802, 5594160114, 25382926322, 113581912050, 502582927346, 2203470381042, 9586688622578, 41438522310642, 178122308583410, 761964546228210, 3245764578377714 (list; graph; refs; listen; history; text; internal format)
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.

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

AUTHOR

Emeric Deutsch, Apr 06 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 21 19:21 EST 2022. Contains 350480 sequences. (Running on oeis4.)