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
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
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jul 13 2013
STATUS
approved