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A227485
The hyper-Wiener index of the dendrimer D_4[n], defined pictorially in the A. R. Ashrafi et al. reference.
1
1165, 795061, 19190411, 222761135, 1865766759, 13037931735, 81350611063, 470142180535, 2571969023543, 13504663462199, 68693896897335, 340717322458935, 1655620816211767, 7909483093294903, 37250047530671927, 173305467651546935, 797871121068613431, 3639796169374261047
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.
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
Sequence in context: A223800 A244428 A221350 * A252009 A032744 A185477
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jul 13 2013
STATUS
approved