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).

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

Table of n, a(n) for n=1..25.

I. Gutman, S. Klavzar, An algorithm for the calculation of the Szeged index of benzenoid hydrocarbons, preprint.

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 * A291071 A254620 A299862

Adjacent sequences: A245828 A245829 A245830 * A245832 A245833 A245834

Keyword

nonn

Author

Emeric Deutsch, Aug 07 2014

Status

approved