login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A224429 The Wiener index of the dendrimer D_1[n], defined pictorially in the A. R. Ashrafi et al. reference. 1
84, 18327, 233565, 1771209, 10839249, 59193537, 301745505, 1470068769, 6938902689, 32002414497, 145020899745, 648175476129, 2865160922529, 12550658135457, 54563037754785, 235694448080289, 1012548295652769, 4329277751424417, 18433454242526625 (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, N0. 2, 2012, 127-130.

LINKS

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

FORMULA

a(n) = - 2655 + 26907*2^n + 16245*n*4^n -24168*4^n -570*n*2^n.

G.f. = 3(28+5745z+230z^2-34880z^3+20912z^4)/[(1-z)(1-2z)^2*(1-4z)^2].

MAPLE

a := proc (n) options operator, arrow: -2655+26907*2^n+16245*4^n*n-24168*4^n-570*2^n*n end proc: seq(a(n), n = 0 .. 18);

CROSSREFS

Cf. A224430

Sequence in context: A265586 A278725 A186245 * A289325 A202923 A232914

Adjacent sequences:  A224426 A224427 A224428 * A224430 A224431 A224432

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 July 8 07:34 EDT 2020. Contains 335513 sequences. (Running on oeis4.)