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 re: computer can't go that high
I see the prime divisor function (PRMDIV) in UBASIC doesn't even try with numbers as large as the 10513391193507374500051862069 that's encountered when x=28, which is why my program missed it.
Posted by Charlie
on 2010-07-30 18:17:40