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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
> 
> 


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