400以内（1~400内的）的质数有78个。即：
2、3.5.7.11.13.17.19.23.29.31.37.41.43.47.53.59.61.67.71.73.79.83.89.97.
101.103.107.109.113.131.137.139.147.149.151.157.163.167.173.179.181.191.193.197.199.
211.223.227.229.233.239.241.251.257.263.269.271.277.281.283.293.
307.311.313.317.331.337.347.349.353.359.367.373.379.383.389.397。
