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RE: Sum of Prime factors

  • To: mathgroup at smc.vnet.net
  • Subject: [mg30864] RE: [mg30809] Sum of Prime factors
  • From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.de>
  • Date: Fri, 21 Sep 2001 04:04:02 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

> -----Original Message-----
> From: Shyam Sunder Gupta [mailto:cec at cal2.vsnl.net.in]
To: mathgroup at smc.vnet.net
> Sent: Wednesday, September 19, 2001 6:17 AM
> Subject: [mg30864] [mg30809] Sum of Prime factors
> 
> 
> 
> Can any body help in providing a simple mathematica code for 
> finding sum 
> of digits of prime factors(including repetitions) of a number. For 
> example 198 =2*3*3*11 , so sum of digits of prime factors= 
> 2+3+3+1+1=10.
> 
> Shyam Sunder Gupta
> email: guptass at rediffmail.com
> 

Not being shure what you want to attain, please try 

Plus @@ Times @@@ FactorInteger[a]
Plus @@ Flatten@(IntegerDigits /@ Times @@@ FactorInteger[a])
Plus @@ Flatten@(IntegerDigits[#1]*#2 & @@@ FactorInteger[a])

All these function coincide on a=35, the last two on a = 198, and
all differ at a=56491710780978

-- Hartmut Wolf



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