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A123351 Kekulé numbers for certain benzenoids (see the Cyvin-Gutman book for details). 2
1, 4, 30, 146, 517, 1476, 3614, 7890, 15761, 29332, 51526, 86274, 138725, 215476, 324822, 477026, 684609, 962660, 1329166, 1805362, 2416101, 3190244, 4161070, 5366706, 6850577, 8661876, 10856054, 13495330, 16649221, 20395092, 24818726 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..30.

S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (see p. 120 and K{Ch(m,3)} page 119).

FORMULA

G.f.: -x*(2*x^6-8*x^5+20*x^4-15*x^3+23*x^2-3*x+1) / (x-1)^7. - Colin Barker, Aug 29 2013

MAPLE

A123351 := proc(n)

    (n^6+6*n^5+22*n^4+30*n^3+49*n^2+36)/36 ;

end proc:

seq( A123351(n), n=0..30) ; # R. J. Mathar, Jul 26 2019

CROSSREFS

Sequence in context: A316178 A305764 A317113 * A305525 A316999 A217213

Adjacent sequences:  A123348 A123349 A123350 * A123352 A123353 A123354

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Oct 10 2006

STATUS

approved

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Last modified October 27 09:36 EDT 2021. Contains 348272 sequences. (Running on oeis4.)