Re: simplifying a summation / integral

*To*: mathgroup at smc.vnet.net*Subject*: [mg64783] Re: simplifying a summation / integral*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Thu, 2 Mar 2006 19:28:00 -0500 (EST)*Organization*: The Open University, Milton Keynes, UK*References*: <du6nqk$5ob$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Patrik wrote: > I need a simple closed form expression for: > > Sum [(qCr)*(x^r)/r] > where qCr is q choose r, i.e., (q!/(r!(q-r)!) > and r is summed from 1 to q > > Any thoughts? Hi Patrik, Do you mean something like that? In[1]:= Sum[Binomial[q, r]*(x^r/r), {r, 1, q}] Out[1]= q*x*HypergeometricPFQ[{1, 1, 1 - q}, {2, 2}, -x] Best regards, /J.M.