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Search: id:A107971
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| A107971 |
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(1/720)(n+1)(n+2)(n+3)(35n^3+153n^2+232n+120). |
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+0
1
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| 1, 18, 123, 523, 1673, 4424, 10206, 21246, 40821, 73546, 125697, 205569, 323869, 494144, 733244, 1061820, 1504857, 2092242, 2859367, 3847767, 5105793, 6689320, 8662490, 11098490, 14080365, 17701866, 22068333, 27297613, 33521013, 40884288
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Kekule numbers for certain benzenoids.
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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 (p. 230).
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FORMULA
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O.g.f.: -(1+11x+18x^2+5x^3)/(-1+x)^7. a(n)=A107962(n)-A107962(n-1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 07 2008
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MAPLE
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a:=n->(1/720)*(n+1)*(n+2)*(n+3)*(35*n^3+153*n^2+232*n+120): seq(a(n), n=0..35);
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CROSSREFS
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Sequence in context: A044731 A108648 A037064 this_sequence A002424 A101378 A107417
Adjacent sequences: A107968 A107969 A107970 this_sequence A107972 A107973 A107974
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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), Jun 12 2005
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