Mersenne prime Mersenne prime In mathematics, a Mersenne prime is a prime number that is one less than a power of two. That is, it is a prime number of the form for some integer . They are named after Marin Mersenne, a French Minim friar, who studied them in the early 17th century. The exponents which give Mersenne primes are 2, 3, 5, 7, 13, 17, 19, 31, ... and the resulting Mersenne primes are 3, 7, 31, 127, 8191, 131071, 524287, 2147483647, ... . If is a composite number then so is . ( is divisible by both and .)
Prime number such as the Meissel–Lehmer algorithm can compute exact values of formula_88 faster than it would be possible to list each prime up to formula_1. The prime number theorem states that formula_88 is asymptotic to formula_94, which is denoted as and means that the ratio of formula_88 to the right-hand fraction approaches 1 as formula_1 grows to infinity. This implies that the likelihood that a randomly chosen number less than formula_1 is prime is (approximately) inversely proportional to the number of digits in formula_1. It also implies that the formula_1th prime number is proportional to formula_101 and therefore that the average