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 A114239 a(n) = (n+1)(n+2)^3*(n+3)(n^2 + 4n + 5)/120. 3
 1, 18, 136, 650, 2331, 6860, 17472, 39852, 83325, 162382, 298584, 522886, 878423, 1423800, 2236928, 3419448, 5101785, 7448874, 10666600, 15008994, 20786227, 28373444, 38220480, 50862500, 66931605, 87169446, 112440888, 143748766 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Kekulé numbers for certain benzenoids. First differences of A107891. Partial sums of A083200. - Peter Bala, Sep 21 2007 REFERENCES S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (see p. 167, Table 10.5/I/6). LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 FORMULA a(n-2) = (n^7-n^3)/(2^7-2^3). - David Radcliffe, Dec 27 2008 G.f.: (1+10*x+20*x^2+10*x^3+x^4)/(1-x)^8. - Colin Barker, Feb 09 2012 MAPLE a:=n->(n+1)*(n+2)^3*(n+3)*(n^2+4*n+5)/120: seq(a(n), n=0..33); PROG (PARI) a(n)=n-=2; (n^7-n^3)/120 \\ Charles R Greathouse IV, Feb 09 2012 CROSSREFS Cf. A047819, A083200, A107891. Sequence in context: A056003 A337002 A239208 * A087115 A163707 A212154 Adjacent sequences:  A114236 A114237 A114238 * A114240 A114241 A114242 KEYWORD nonn,easy AUTHOR Emeric Deutsch, Nov 18 2005 STATUS approved

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Last modified December 3 10:45 EST 2021. Contains 349462 sequences. (Running on oeis4.)