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 A205825 a(n) = n!/ceiling(n/2)!. 3
 1, 1, 2, 3, 12, 20, 120, 210, 1680, 3024, 30240, 55440, 665280, 1235520, 17297280, 32432400, 518918400, 980179200, 17643225600, 33522128640, 670442572800, 1279935820800, 28158588057600, 53970627110400, 1295295050649600, 2490952020480000, 64764752532480000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Table of n, a(n) for n=0..26. FORMULA E.g.f.: (exp(x^2)*(x+1) -1)/x. - Sergei N. Gladkovskii, Oct 10 2012 Sum_{n>=0} 1/a(n) = 3/2 + 5*exp(1/4)*sqrt(Pi)*erf(1/2)/4, where erf is the error function. - Amiram Eldar, Feb 13 2023 MATHEMATICA Table[n!/Ceiling[n/2]!, {n, 0, 24}] CROSSREFS Cf. A205785, A205786. Sequence in context: A067391 A096361 A105045 * A076000 A096632 A124261 Adjacent sequences: A205822 A205823 A205824 * A205826 A205827 A205828 KEYWORD nonn AUTHOR Clark Kimberling, Feb 01 2012 EXTENSIONS a(0)=1 prepended and e.g.f. edited by Alois P. Heinz, Sep 08 2015 STATUS approved

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Last modified September 11 17:05 EDT 2024. Contains 375838 sequences. (Running on oeis4.)