Re: Summations with Primes

*To*: mathgroup at smc.vnet.net*Subject*: [mg39961] Re: [mg39932] Summations with Primes*From*: Sseziwa Mukasa <mukasa at jeol.com>*Date*: Thu, 13 Mar 2003 03:02:44 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

On Wednesday, March 12, 2003, at 02:29 AM, Anthony Felder wrote: > > Can you tell me if, when calculating a summation of f(i) where i goes > from > imin to imax, Mathematica can be forced to only use prime values for i? > > Thank you for your time > > Anthony Felder > > > Two options: This function returns the number of primes including the smallest prime greater than or equal to n. primeceiling[n_Integer]:=PrimePi[n]+If[PrimeQ[n],0,1] You can use it to compute the sum as follows Sum[f[Prime[i]],{i, or you can simply check if i is prime Sum[If[PrimeQ[i],f[i],0],{i,imin,imax}] Regards, Ssezi