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Re: Summation question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg85706] Re: Summation question
  • From: dh <dh at metrohm.ch>
  • Date: Tue, 19 Feb 2008 07:07:21 -0500 (EST)
  • References: <fpdu7v$qlq$1@smc.vnet.net>


Hi Robert,

applying Prime to a range of integers gives the prime indices (note that 

by definition 1 is not but 2 is prime). Then we map f onto these primes 

and finally use Total to get the sum:

Total[f /@ Prime@Range[6]]

hope this helps, Daniel





Robert Pigeon wrote:

> Good day all,

> 

>             I want to make a summation like this:  Sum[f[i],{i, start,

> finish}]. What I want is that the sum be over a specific set like

> {1,3,5,7,11,13}. So the sum would be : f[1]+f[3]+f[5]+f[7]+f[11]+f[13]. The

> set I want to use is the primes. So, how do I use, if possible, Sum over a

> specific set ?

> 

>  

> 

> Thanks,

> 

>  

> 

> Robert

> 

>  

> 

> Robert Pigeon

> 

> 




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