Re: Bug in Sum?

*To*: mathgroup at smc.vnet.net*Subject*: [mg119925] Re: Bug in Sum?*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 30 Jun 2011 06:29:34 -0400 (EDT)*Reply-to*: hanlonr at cox.net

For a workaround, generalize the problem Sum[1/(n (1 + n)) 1/((1 - x)^r), {n, 1, M}] M/((1 - x)^r*(1 + M)) % /. r -> 4 M/((1 + M)*(1 - x)^4) Bob Hanlon ---- Dario <dario.benedetti at aei.mpg.de> wrote: ============= I am very puzzled by the fact that Mathematica does not evaluate the following Sum (it keeps running endlessly): Sum[1/(n (1 + n)) 1/((1 - x)^4) , {n, 1, M}] where x and M are some undefined variables, but it does evaluate Sum[1/(n (1 + n)) 1/((1 - x)^2) , {n, 1, M}] where I have only changed the power of (1-x), which should not matter as it must factor out! Any help on this please?

**Follow-Ups**:**Re: Bug in Sum?***From:*Phil J Taylor <xptaylor@gmail.com>