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A110696 Kekulé numbers for certain benzenoids of trigonal symmetry. 1
1, 28, 1456, 66178, 3014128, 143076778, 7087202890, 363641489638, 19183237689328, 1034361829223578, 56758935931548706, 3159417013205183638, 177966175592478108106, 10125526670502832205398, 581051793331857091649398 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
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
FORMULA
a(n) = 9*binomial(2n, n)^3 - 15*binomial(2n, n)^2 + 9*binomial(2n, n) - 2.
MAPLE
a:=n->9*binomial(2*n, n)^3-15*binomial(2*n, n)^2+9*binomial(2*n, n)-2; seq(a(n), n=0..16);
MATHEMATICA
Table[9*Binomial[2*n, n]^3 - 15*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(9*binomial(2n, n)^3 - 15*binomial(2n, n)^2 + 9*binomial(2n, n) - 2, ", ")) \\ G. C. Greubel, Sep 06 2017
CROSSREFS
Sequence in context: A249348 A366302 A013926 * A007222 A209265 A042515
KEYWORD
nonn
AUTHOR
Emeric Deutsch, Aug 03 2005
STATUS
approved

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Last modified April 12 22:48 EDT 2024. Contains 371639 sequences. (Running on oeis4.)