A143369 The Szeged index of fourth type dendrimer nanostar which has grown n stages.

36604, 304804, 2137492, 13143988, 73561204, 385003252, 1919944180, 9239885812, 43293991924, 198728338420, 897605155828, 4002258869236, 17658743397364, 77238940933108, 335382756072436, 1447262942927860, 6212030751579124, 26540148350000116, 112928927250390004

Offset

1,1

Links

Table of n, a(n) for n=1..19.

A. Iranmanesh and N. Gholami, Computing the Szeged index of third and fourth dendrimer nanostars, Micro & Nano Letters, 2 (2007), 107-110.

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

Formula

a(n) = 24624*n*4^n + 7156 + 25992*n*2^n + 53532*2^n - 57024*4^n.

G.f.: -4*x*(58624*x^4-138336*x^3+129424*x^2-42762*x+9151) / ((x-1)*(2*x-1)^2*(4*x-1)^2). - Colin Barker, Sep 20 2013

Maple

a:=24624*n*4^n+7156+25992*n*2^n+53532*2^n-57024*4^n: seq(a(n), n=1..18);

Crossrefs

Cf. A143367.

Sequence in context: A011770 A250540 A251797 * A203939 A061739 A232135

Adjacent sequences: A143366 A143367 A143368 * A143370 A143371 A143372

Keyword

nonn,easy

Author

Emeric Deutsch, Sep 05 2008

Extensions

More terms from Colin Barker, Sep 20 2013

Status

approved