A216122 The Wiener index of the nanostar dendrimer NS[n], defined pictorially in the Ashrafi et al. reference.

94698, 1317858, 10315218, 63835698, 349594098, 1781094258, 8661794418, 40799683698, 187793424498, 849479276658, 3790907541618, 16734956611698, 73223518070898, 318024922835058, 1372613885896818, 5892491154499698, 25178059222493298, 107144508620089458

Offset

1,1

Comments

a(1) has been checked by the direct computation of the Wiener index (using Maple).

Links

Table of n, a(n) for n=1..18.

A. R. Ashrafi and M. Mirzagar, PI, Szeged and edge Szeged indices of an infinite family of nanostar dendrimers, Indian J. of Chemistry, 47A, 2008, 538-541.

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.

J. Yang, F. Xia, and S. Chen, Second-order and third-order connectivity indices of an infinite family of dendrimer nanostars, Int. J. Contemp. Math. Sciences, 6, 2011, No. 5, 215-220.

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

Formula

a(n) = -55182 + 181020*2^n - 125640*4^n -42000*n*2^n +93600*n*4^n.

G.f.: -6*x*(2112*x^4+10912*x^3-126044*x^2+14464*x+15783) / ((x-1)*(2*x-1)^2*(4*x-1)^2). - Colin Barker, Apr 01 2013

Maple

a := proc (n) options operator, arrow: -55182+181020*2^n-125640*4^n+93600*4^n*n-42000*2^n*n end proc: seq(a(n), n = 1 .. 18);

Crossrefs

Cf. A216123.

Sequence in context: A252323 A030091 A128376 * A206411 A128389 A258420

Adjacent sequences: A216119 A216120 A216121 * A216123 A216124 A216125

Keyword

nonn,easy

Author

Emeric Deutsch, Mar 25 2013

Status

approved