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-   -   Thread for posting tiny primes (https://www.mersenneforum.org/showthread.php?t=13650)

science_man_88 2010-09-22 19:54

because I would never know when all candidates end so I could never stop.

CRGreathouse 2010-09-22 20:04

[QUOTE=science_man_88;230969]because I would never know when all candidates end so I could never stop.[/QUOTE]

What does that even mean? "when all candidates end"


OK, maybe I need to find something easier, or at least different. How about this: you know how to calculate the odds of finding 0 primes with a given N and L. Can you create a function that reverses this? Say someone wants to sieve a range to a given L such that the range contains 0 primes with probability 1% (that is, the range is 99% likely to have primes).

science_man_88 2010-09-22 20:37

well the probability that a candidate isn't prime is the opposite to if it is so reverse the fraction:

[CODE](17:36) gp > poisson3(N,t,n) = n!/(((t/log(N))^n)*exp(-(t/log(N))))
%260 = (N,t,n)->n!/(((t/log(N))^n)*exp(-(t/log(N))))[/CODE]

CRGreathouse 2010-09-22 20:52

I was looking for a function that, given a probability p (and N, t, L), would give an n such that

estimatePrimes(N,t,n,L)

is 1 - p.

3.14159 2010-09-22 21:18

Submissions: 37092 * 56087[sup]2890[/sup] + 1 (13729 digits)

Prime with prime number of digits.

Qualified for item 5.

science_man_88 2010-09-22 22:55

if we could reverse engineer the first to find n we won't need to use L

science_man_88 2010-09-22 23:24

did I mention the hard part is getting the last n out of the logarithm lol

CRGreathouse 2010-09-22 23:26

[QUOTE=science_man_88;231003]if we could reverse engineer the first to find n we won't need to use L[/QUOTE]

No, because you get different n depending on L.

Suppose N = 10^100. If L < 2 then n is 1064: you need to pick 1064 numbers near a googol to find a prime with 99% certainty. If L = 1000, then n is 87: you don't need to pick nearly so many numbers if you know that none have prime divisors smaller than a thousand.

3.14159 2010-09-22 23:26

Is the above the code for Charles's (grammatical error?) request?

3.14159 2010-09-22 23:27

[QUOTE=Charles]Suppose N = 10^100. If L < 2 then n is 1064: you need to pick 1064 numbers near a googol to find a prime with 99% certainty. If L = 1000, then n is 87: you don't need to pick nearly so many numbers if you know that none have prime divisors smaller than a thousand.
[/QUOTE]

How about if I knew the numbers in question had no divisors smaller than 167772161?

CRGreathouse 2010-09-22 23:33

[QUOTE=3.14159;231010]How about if I knew the numbers in question had no divisors smaller than 167772161?[/QUOTE]

Maybe you can ask sm that question once he finishes the script!

[SPOILER]32[/SPOILER]


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