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A110698
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Kekule numbers for certain benzenoids of trigonal symmetry.
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0
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9, 104, 3724, 152978, 6772428, 318919354, 15762420826, 808272767014, 42631956711628, 2298618088718378, 126131492134695474, 7020934326396461014, 395480502329858803674, 22501172037539767125398
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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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)=20*binomial(2n, n)^3-18*binomial(2n, n)^2+9*binomial(2n, n)-2.
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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);
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CROSSREFS
| Sequence in context: A183518 A083452 A081461 * A012485 A052503 A122569
Adjacent sequences: A110695 A110696 A110697 * A110699 A110700 A110701
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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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