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Search: id:A108681
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| A108681 |
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(n+1)(n+2)^2*(n+3)(n+4)(n+5)(2n+3)/720. |
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+0
1
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| 1, 15, 98, 420, 1386, 3822, 9240, 20196, 40755, 77077, 138138, 236600, 389844, 621180, 961248, 1449624, 2136645, 3085467, 4374370, 6099324, 8376830, 11347050, 15177240, 20065500, 26244855, 33987681, 43610490, 55479088, 70014120
(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.232, # 4).
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FORMULA
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G.f.=(1+z)(1+6z)/(1-z)^8
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MAPLE
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G:=factor(sum(a(n)*z^n, n=0..infinity)); series(G, z=0, 37);
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CROSSREFS
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Adjacent sequences: A108678 A108679 A108680 this_sequence A108682 A108683 A108684
Sequence in context: A052459 A044266 A044647 this_sequence A108254 A000973 A034266
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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 18 2005
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