A227485 - OEIS

A227485

The hyper-Wiener index of the dendrimer D_4[n], defined pictorially in the A. R. Ashrafi et al. reference.

1165, 795061, 19190411, 222761135, 1865766759, 13037931735, 81350611063, 470142180535, 2571969023543, 13504663462199, 68693896897335, 340717322458935, 1655620816211767, 7909483093294903, 37250047530671927, 173305467651546935, 797871121068613431, 3639796169374261047

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OFFSET

0,1

COMMENTS

a(1) has 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..17.

Index entries for linear recurrences with constant coefficients, signature (19,-150,636,-1560,2208,-1664,512).

FORMULA

a(n) = 1007415 + 2^n*(-4509545 + 732099*n - 171585*n^(2)) + 4^n*(3503295 -2446768*n + 864900*n^(2)).

G.f.: (1165 + 772926*z + 4259002*z^2 - 23338464*z^3 + 8025448*z^4 + 35155008*z^5 + 2325120*z^6)/((1-z)*(1-2*z)^3*(1-4*z)^3).

MAPLE

a := proc (n) options operator, arrow: 1007415+2^n*(-4509545+732099*n-171585*n^2)+4^n*(3503295-2446768*n+864900*n^2) end proc: seq(a(n), n = 0 .. 20);

CROSSREFS

Cf. A227484

Sequence in context: A223800 A244428 A221350 * A252009 A032744 A185477

Adjacent sequences: A227482 A227483 A227484 * A227486 A227487 A227488

KEYWORD

nonn,easy

AUTHOR

Emeric Deutsch, Jul 13 2013

STATUS

approved