A221006 The Wiener index of the nanostar dendrimer NS[n], defined pictorially in the Karbasioun-Ashrafi-Diudea reference.

1296, 14526, 107082, 649890, 3539538, 18027954, 87813234, 414505458, 1911928050, 8665131762, 38733797106, 171235454706, 750157258482, 3261519544050, 14089697722098, 60533384085234, 258832139157234, 1102123427954418, 4675674117242610, 19771419930918642, 83360577251966706

Offset

0,1

Links

Table of n, a(n) for n=0..20.

A. Karbasioun, A. R. Ashrafi, and M. V. Diudea, Distance and detour matrices of an infinite class of dendrimer nanostars, MATCH Commun. Math. Comput. Chem. 63, 2010, 239-246.

Index entries for linear recurrences with constant coefficients, signature (11,-42,64,-32).

Formula

a(n) = -270 + 2^n*3510+4^n*(3888*n-1944) (see Theorem 1 in the Karbasioun-Ashrafi-Diudea reference).

G.f.: -54*(16*x^3-32*x^2-5*x-24) / ((x-1)*(2*x-1)*(4*x-1)^2). [Colin Barker, Jan 01 2013]

Maple

a := proc (n) options operator, arrow: -270+3510*2^n+4^n*(3888*n-1944) end proc: seq(a(n), n = 0 .. 20);

Crossrefs

Cf. A221007.

Sequence in context: A137488 A189991 A250438 * A016864 A064785 A223560

Adjacent sequences: A221003 A221004 A221005 * A221007 A221008 A221009

Keyword

nonn,easy

Author

Emeric Deutsch, Dec 29 2012

Status

approved