For a positive integer x drawn at random between 1 and 20000 inclusively, determine the probability that (x!+1)/(x+1) is a prime number.
(In reply to mathematica solutions (so far)
Nice find Daniel.
I am giving up on a (quick) solution to this, as rather than find a program already made to determine if a number is a Strong Probable Prime, I got sidetracked and began trying to code my own. I had to learn about modular exponentiation, and brush up on my Python skills just to code a very rough version of the algorithm on Wikipedia.
I learned that Python 3 no longer likes large integers, and had to write another function, just to break down my values into chunks that it could work with. All of this "wasted" time for a program that can't compare to even the most horribly coded (but functional) version of the algorithm when done in C++. Is it time to relearn the language? I think so!
So, thanks to this problem's ability to get me thinking (and learning), I decided to rate it very highly (perhaps influenced further by my love of prime numbers). Hopefully we're able to come to a conclusion as to what the final answer is sometime in the near future.
Posted by Justin
on 2010-07-31 03:57:51