素数是数学中最重要、最基本的概念之一．关于素数个数的讨论，早在两千多年前，古希腊学者欧几里得（Ｅｕｃｌｉｄ）已在其名著《几何原本》中给出且证明：素数有无穷多个．人们又发现素数在自然数中所占比例很小，若记π（ｘ）为不超过ｘ的素数个数，数学大师欧拉（Ｌ．Ｅｕ Prime number is one of the most important and basic concepts in mathematics. With regard to the discussion of the number of primes, as early as two thousand years ago, the ancient Greek scholar Euclid has given and proved in his famous book “Geometry Original” that there are infinitely many prime numbers. People also find that the proportion of prime numbers in natural numbers is very small. If you remember that π(x) is a number of primes that does not exceed x, mathematician Euler (L.Eu)