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Search: id:A109124
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| A109124 |
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(n+1)(n+2)^3*(n+3)^4*(n+4)^3*(n+5)(2n+5)(2n+7)/7257600. |
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+0
1
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| 1, 90, 2475, 35035, 321048, 2159136, 11511720, 51210225, 196994655, 672567610, 2078241165, 5900460930, 15576433600, 38599672320, 90491328576, 201987412398, 431582100885, 886725689850, 1758635878615, 3378012822261, 6302164837320
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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.186, D(4,5,n)).
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FORMULA
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G.f.=(1+z)(1+74z+1156z^2+5749z^3+10064z^4+5749z^5+1156z^6+74z^7+z^8)/(1-z)^15.
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MAPLE
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a:=n->(n+1)*(n+2)^3*(n+3)^4*(n+4)^3*(n+5)*(2*n+5)*(2*n+7)/7257600: seq(a(n), n=0..23);
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CROSSREFS
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Sequence in context: A065951 A008393 A055603 this_sequence A013359 A013355 A013357
Adjacent sequences: A109121 A109122 A109123 this_sequence A109125 A109126 A109127
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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 20 2005
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