Re: Summation problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg56636] Re: Summation problem*From*: "Dr. Wolfgang Hintze" <weh at snafu.de>*Date*: Sun, 1 May 2005 00:46:33 -0400 (EDT)*References*: <d4v6br$nq9$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

(Knowing that statetments like this don't really help) I cannot spot the problem In[1]:= Sum[I^n/n, {n, 1, Infinity}] Out[1]= -Log[1 - I] In[2]:= Sum[I^(n + 1)/n, {n, 1, Infinity}] Out[2]= -I*Log[1 - I] In[3]:= $Version Out[3]= "4.0 for Microsoft Windows (April 21, 1999)" Regards, Wolfgang jaropis wrote: > Why can't Mathematica sum: > Sum[I^n/n,{n,1,Infinity}] > and gives the (incorrect) answer, that this is divergent while it can do: > Sum[I^(n+1)/n,{n,1,Infinity}] > correctly? > > Jaroslaw Piskorski > >