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 A110698 Kekulé numbers for certain benzenoids of trigonal symmetry. 1
 9, 104, 3724, 152978, 6772428, 318919354, 15762420826, 808272767014, 42631956711628, 2298618088718378, 126131492134695474, 7020934326396461014, 395480502329858803674, 22501172037539767125398 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 REFERENCES S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (see p. 313). LINKS G. C. Greubel, Table of n, a(n) for n = 0..550 FORMULA a(n) = 20*binomial(2n, n)^3 - 18*binomial(2n, n)^2 + 9*binomial(2n, n) - 2. MAPLE a:=n->20*binomial(2*n, n)^3-18*binomial(2*n, n)^2+9*binomial(2*n, n)-2; seq(a(n), n=0..16); MATHEMATICA Table[20*Binomial[2*n, n]^3 - 18*Binomial[2*n, n]^2 + 9*Binomial[2*n, n] - 2, {n, 0, 50}] (* G. C. Greubel, Sep 06 2017 *) PROG (PARI) for(n=0, 25, print1(20*binomial(2n, n)^3 - 18*binomial(2n, n)^2 + 9*binomial(2n, n) - 2, ", ")) \\ G. C. Greubel, Sep 06 2017 CROSSREFS Sequence in context: A083452 A081461 A231646 * A012485 A052503 A261428 Adjacent sequences:  A110695 A110696 A110697 * A110699 A110700 A110701 KEYWORD nonn AUTHOR Emeric Deutsch, Aug 03 2005 STATUS approved

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Last modified February 26 05:51 EST 2020. Contains 332277 sequences. (Running on oeis4.)