## Again primes

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• Puzzle: Prove (but not experimentally) that there is a value of t for which (2/3)*sqrt(6*t+1)*cos(arc cos(27*t^2+18*t-25)/(2*(6*t+1)^(3/2)))/3)+1/3 is a prime
Message 1 of 33 , Oct 30, 2011
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Puzzle: Prove (but not experimentally) that there is a value of t for which

(2/3)*sqrt(6*t+1)*cos(arc cos(27*t^2+18*t-25)/(2*(6*t+1)^(3/2)))/3)+1/3

is a prime number.

Proving by classical means that for this value of t , this prime number is unique is certainly much more difficult.
• ... I saw that, thanks David! Since this is a list dedicated to primes, I ll also just mention briefly that yafu has one of the fastest sieve of Eratosthenes
Message 33 of 33 , Nov 8, 2011
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--- In primenumbers@yahoogroups.com, David Cleaver <wraithx@...> wrote:
>
>

>
> Ben, I've been trying to tell them how awesome Yafu is! You can see my message
> here:
>
> If anyone needs any factoring utilities, yafu should be first on the list. Then
> some combination of yafu/msieve/ggnfs to factor larger numbers. I tried to
> spell it all out in the above post. Hopefully I didn't misrepresent any info
> about yafu. Please correct me if I was wrong. If anyone has any questions,
> feel free to ask on this list.
>
> -David C.
>
> P.S. For full disclosure, I helped contribute a small amount of code to yafu. :)
>

I saw that, thanks David!

Since this is a list dedicated to primes, I'll also just mention briefly that yafu has one of the fastest sieve of Eratosthenes implementations I'm aware of, for generating lists of primes in arbitrary ranges up to 10^19. Maybe that is useful to folks here too.

cheers,
- ben.
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