A224432 The hyper-Wiener index of the dendrimer D_2[n], defined pictorially in the A. R. Ashrafi et al. reference.

622, 28413, 426343, 4177227, 32549395, 220006179, 1351039555, 7748170371, 42234607363, 221419948035, 1125752748547, 5584044867075, 27143513179651, 129736439305731, 611327539426819, 2845765137102339, 13108587035424259, 59831264715339267

Offset

0,1

Comments

a(2) has been checked by the direct computation of the hyper-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..17.

Formula

a(n) = - 2557 - 76735*2^n - 9768*2^n*n - 44640*4^n*n + 79914*4^n + 14400*4^n*n^2 + 2640*2^n*n^2.

G.f.=(622+16595z-20204z^2-56932z^3+33184z^4-51520z^5+9216z^6)/[(1-z)(1-2z)^3(1-4z)^3].

Maple

a := proc (n) options operator, arrow: -2557-76735*2^n-9768*2^n*n-44640*4^n*n+79914*4^n+14400*4^n*n^2+2640*2^n*n^2 end proc: seq(a(n), n = 0 .. 17);

Crossrefs

Cf. A224431

Sequence in context: A251243 A184226 A260764 * A229318 A268025 A207554

Adjacent sequences: A224429 A224430 A224431 * A224433 A224434 A224435

Keyword

nonn

Author

Emeric Deutsch, Apr 06 2013

Status

approved