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A193393
Wiener index of a benzenoid consisting of a zig-zag chain of n hexagons (s=13; see the Gutman et al. reference).
8
27, 109, 271, 545, 963, 1557, 2359, 3401, 4715, 6333, 8287, 10609, 13331, 16485, 20103, 24217, 28859, 34061, 39855, 46273, 53347, 61109, 69591, 78825, 88843, 99677, 111359, 123921, 137395, 151813, 167207, 183609, 201051, 219565, 239183, 259937, 281859, 304981, 329335, 354953
OFFSET
1,1
LINKS
A. A. Dobrynin, I. Gutman, S. Klavzar, P. Zigert, Wiener Index of Hexagonal Systems, Acta Applicandae Mathematicae 72 (2002), pp. 247-294.
I. Gutman, S. Klavzar, M. Petkovsek, and P. Zigert, On Hosoya polynomials of benzenoid graphs, Comm. Math. Comp. Chem. (MATCH), 43, 2001, 49-66.
FORMULA
a(n) = (16*n^3 + 24*n^2 + 62*n - 21)/3.
G.f.: x*(27 + x - 3*x^2 + 7*x^3)/(1-x)^4. - Bruno Berselli, Jul 27 2011
PROG
(Magma) [(16*n^3 + 24*n^2 + 62*n - 21)/3: n in [1..40]]; // Vincenzo Librandi, Jul 26 2011
(PARI) a(n)=(16*n^3+24*n^2+62*n)/3-7 \\ Charles R Greathouse IV, Jul 26 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jul 25 2011
STATUS
approved