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Search: id:A110697
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| A110697 |
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Kekule numbers for certain benzenoids of trigonal symmetry. |
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+0
1
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| 2, 35, 1547, 67319, 3028619, 143266535, 7089761447, 363676815215, 19183734561419, 1034368920790919, 56759038335333047, 3159418506105987215, 177966197529849012647, 10125526995020242083599, 581051798159881757979599
(list; graph; listen)
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OFFSET
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0,1
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REFERENCES
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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
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a(n)=9*binomial(2n, n)^3-12*binomial(2n, n)^2+6*binomial(2n, n)-1.
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MAPLE
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a:=n->9*binomial(2*n, n)^3-12*binomial(2*n, n)^2+6*binomial(2*n, n)-1; seq(a(n), n=0..16);
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CROSSREFS
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Sequence in context: A055519 A112442 A066549 this_sequence A132100 A133013 A032369
Adjacent sequences: A110694 A110695 A110696 this_sequence A110698 A110699 A110700
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KEYWORD
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nonn
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 03 2005
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