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A224429
The Wiener index of the dendrimer D_1[n], defined pictorially in the A. R. Ashrafi et al. reference.
1
84, 18327, 233565, 1771209, 10839249, 59193537, 301745505, 1470068769, 6938902689, 32002414497, 145020899745, 648175476129, 2865160922529, 12550658135457, 54563037754785, 235694448080289, 1012548295652769, 4329277751424417, 18433454242526625
OFFSET
0,1
COMMENTS
a(2) 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) = - 2655 + 26907*2^n + 16245*n*4^n -24168*4^n -570*n*2^n.
G.f. = 3(28+5745z+230z^2-34880z^3+20912z^4)/[(1-z)(1-2z)^2*(1-4z)^2].
MAPLE
a := proc (n) options operator, arrow: -2655+26907*2^n+16245*4^n*n-24168*4^n-570*2^n*n end proc: seq(a(n), n = 0 .. 18);
CROSSREFS
Sequence in context: A278725 A186245 A377017 * A289325 A202923 A232914
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Apr 06 2013
STATUS
approved