A224433 The Wiener index of the dendrimer D_3[n], defined pictorially in the A. R. Ashrafi et al. reference.

174, 22734, 299646, 2332398, 14462574, 79461294, 406098606, 1980213678, 9348000174, 43104718254, 195270696366, 872477232558, 3855431404974, 16883645533614, 73381802986926, 316914939973038, 1361207885548974, 5819017520467374, 24772799043194286

Offset

0,1

Comments

a(0) and a(1) have 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)=-12882+44604*2^n-31548*4^n+21780*n*4^n-7260*n*2^n.

G.f.=(6*(29+3412*z+2540*z^2-22296*z^3-3008*z^4))/[(1-z)*(1-2*z)^2*(1-4*z)^2]

Maple

a := proc (n) options operator, arrow: -12882+44604*2^n-31548*4^n+21780*4^n*n-7260*2^n*n end proc: seq(a(n), n = 0 .. 18);

Crossrefs

Cf. A224434

Sequence in context: A248458 A053173 A185525 * A213866 A252717 A187425

Adjacent sequences: A224430 A224431 A224432 * A224434 A224435 A224436

Keyword

nonn

Author

Emeric Deutsch, Apr 06 2013

Status

approved