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 A108678 a(n) = (n+1)^2*(n+2)(2n+3)/6. 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Kekulé numbers for certain benzenoids. REFERENCES S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 232, # 44). LINKS FORMULA G.f.: (1 + 5*x + 2*x^2)/(1-x)^5. a(n) = A098077(n+1)/2. - Alexander Adamchuk, Apr 12 2006 MAPLE 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 MATHEMATICA Table[(n+1)^2*(n+2)(2n+3)/6, {n, 0, 100}] (* Vladimir Joseph Stephan Orlovsky, Jun 03 2011 *) CROSSREFS Cf. A098077. Sequence in context: A031146 A328536 A163815 * A226988 A027171 A003822 Adjacent sequences:  A108675 A108676 A108677 * A108679 A108680 A108681 KEYWORD nonn,easy AUTHOR Emeric Deutsch, Jun 17 2005 STATUS approved

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Last modified December 14 03:31 EST 2019. Contains 329978 sequences. (Running on oeis4.)