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.