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A108678
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a(n) = (n+1)^2*(n+2)(2n+3)/6.
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2
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1, 10, 42, 120, 275, 546, 980, 1632, 2565, 3850, 5566, 7800, 10647, 14210, 18600, 23936, 30345, 37962, 46930, 57400, 69531, 83490, 99452, 117600, 138125, 161226, 187110, 215992, 248095, 283650, 322896, 366080, 413457, 465290, 521850, 583416, 650275, 722722
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OFFSET
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0,2
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COMMENTS
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Kekulé numbers for certain benzenoids.
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REFERENCES
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S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 232, # 44).
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LINKS
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Table of n, a(n) for n=0..37.
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FORMULA
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G.f.: (1 + 5*x + 2*x^2)/(1-x)^5.
a(n) = A098077(n+1)/2. - Alexander Adamchuk, Apr 12 2006
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MAPLE
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a:=n->(n+1)^2*(n+2)*(2*n+3)/6: seq(a(n), n=0..42);
a:=n->sum(n*j^2, j=1..n): seq(a(n), n=1..36); # Zerinvary Lajos, Apr 29 2007
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MATHEMATICA
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Table[(n+1)^2*(n+2)(2n+3)/6, {n, 0, 100}] (* Vladimir Joseph Stephan Orlovsky, Jun 03 2011 *)
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CROSSREFS
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Cf. A098077.
Sequence in context: A031146 A328536 A163815 * A226988 A027171 A003822
Adjacent sequences: A108675 A108676 A108677 * A108679 A108680 A108681
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KEYWORD
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nonn,easy
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AUTHOR
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Emeric Deutsch, Jun 17 2005
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STATUS
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approved
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