       Re: Counting Twin Primes

• To: mathgroup at smc.vnet.net
• Subject: [mg43687] Re: Counting Twin Primes
• From: "Peter Pein" <peter1963 at totalise.co.uk>
• Date: Tue, 30 Sep 2003 16:42:35 -0400 (EDT)
• References: <bkp0dp\$cho\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```tp=TwinPrimes[10^5];
Length[tp]

will give you what you want.

Peter

PS. please excuse the empty post

"Allan Haley" <ashaley at nccn.net> schrieb im Newsbeitrag
news:bkp0dp\$cho\$1 at smc.vnet.net...
> In the Mathematica reference material, there is a defined function to
> list the twin primes in a given interval, as follows:
>
> TwinPrimes[m__] : = Module[{s = Prime[Range[m]]}, {#, # + 2}& /@
Extract[s,
> Position[Drop[s, 1] - Drop[s, -1], 2]]]
>
> My question is: having defined this function and gotten a list for a
> given (large) interval m, how do I get Mathematica to tell me the number
> of twin prime pairs in that interval?  Trying something like
> Count[{TwinPrimes[m]}, _Integer]/2 just gives the output zero.
>