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A245831
The Szeged index of the coronene/circumcoronene benzenoid H_k (see Fig. 5 of the Gutman & Klavzar reference or Fig. 5.7 of the Diudea et al. reference).
0
54, 3438, 39258, 220824, 842850, 2517534, 6349518, 14149728, 28688094, 53985150, 95642514, 161212248, 260605098, 406537614, 615018150, 905871744, 1303303878, 1836503118, 2540282634, 3455760600, 4631079474, 6122164158, 7993519038, 10319063904, 13183008750
OFFSET
1,1
REFERENCES
M. V. Diudea, I. Gutman, J. Lorentz, Molecular Topology, Nova Science Publishers, Huntington, NY (2001).
LINKS
I. Gutman, S. Klavzar, An algorithm for the calculation of the Szeged index of benzenoid hydrocarbons, J. Chem. Inf. Comput. Sci., 35, 1995, 1011-1014.
I. Gutman, P. V. Khadikar, T. Khaddar, Wiener and Szeged indices of benzenoid hydrocarbons containing a linear polyacene fragment, Commun. Math. Chem. (MATCH), 35, 1997, 105-116.
FORMULA
a(k) = 3(36k^6-k^4+k^2)/2.
G.f.: 18z(1+z)(3+167z+740z^2+167z^3+3z^4)/(1-z)^7.
EXAMPLE
a(1)=54; indeed, the benzenoid consists of 1 hexagon and each of its six edges contributes 3*3 towards the Szeged index; 6*9 = 54.
MAPLE
a := proc (n) options operator, arrow: 54*n^6-(3/2)*n^4+(3/2)*n^2 end proc: seq(a(n), n = 1 .. 30);
CROSSREFS
Sequence in context: A309422 A212705 A046199 * A368366 A291071 A254620
KEYWORD
nonn
AUTHOR
Emeric Deutsch, Aug 07 2014
STATUS
approved