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A110696
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Kekule numbers for certain benzenoids of trigonal symmetry.
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0
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1, 28, 1456, 66178, 3014128, 143076778, 7087202890, 363641489638, 19183237689328, 1034361829223578, 56758935931548706, 3159417013205183638, 177966175592478108106, 10125526670502832205398, 581051793331857091649398
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| S. J. Cyvin and I. Gutman, Kekule structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (see p 313).
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FORMULA
| a(n)=9*binomial(2n, n)^3-15*binomial(2n, n)^2+9*binomial(2n, n)-2.
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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);
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CROSSREFS
| Sequence in context: A091993 A118705 A013926 * A007222 A042515 A042512
Adjacent sequences: A110693 A110694 A110695 * A110697 A110698 A110699
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KEYWORD
| nonn
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AUTHOR
| Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 03 2005
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