A143367 The Szeged index of third type dendrimer nanostar which has grown n stages.

9412, 30652, 123148, 564844, 2726572, 13219372, 63206188, 296679724, 1368005932, 6210491692, 27825661228, 123303445804, 541361800492, 2358354445612, 10205728212268, 43913619703084, 188020440958252, 801552290809132, 3404105445803308, 14408036898571564

Offset

1,1

Links

Table of n, a(n) for n=1..20.

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) = 3636*2^n + 1324 + 720*n*4^n + 1560*n*2^n - 1296*4^n.

G.f.: -4*x*(58624*x^4-116832*x^3+81760*x^2-22926*x+2353) / ((x-1)*(2*x-1)^2*(4*x-1)^2). - Colin Barker, Sep 20 2013

Maple

a:=3636*2^n+1324+720*n*4^n+1560*n*2^n-1296*4^n: seq(a(n), n=1..18);

Mathematica

LinearRecurrence[{13, -64, 148, -160, 64}, {9412, 30652, 123148, 564844, 2726572}, 30] (* Harvey P. Dale, Aug 20 2019 *)

Crossrefs

Cf. A143369.

Sequence in context: A264340 A031595 A031775 * A234432 A235677 A235447

Adjacent sequences: A143364 A143365 A143366 * A143368 A143369 A143370

Keyword

nonn,easy

Author

Emeric Deutsch, Sep 05 2008

Extensions

More terms from Colin Barker, Sep 20 2013

Status

approved