Sicily 1009梅森素数

One of the world-wide cooperative computing tasks is the "Grand Internet Mersenne Prime Search" -- GIMPS -- striving to find ever-larger prime numbers by examining a particular category of such numbers. A Mersenne number is defined as a number of the form (2p–1), where p is a prime number -- a number divisible only by one and itself. (A number that can be divided by numbers other than itself and one are called "composite" numbers, and each of these can be uniquely represented by the prime numbers that can be multiplied together to generate the composite number — referred to as its prime factors.) Initially it looks as though the Mersenne numbers are all primes. Prime Corresponding Mersenne Number 2 4–1 = 3 -- prime 3 8–1 = 7