【素数筛法求欧拉值前n项和】POJ 2478 Farey Sequence
http://poj.org/problem?id=2478

Sample Input
2
3
4
5
0

Sample Output
1
3
5
9

求的是：sum(n) = phi(1) + phi(2) + phi(3) + ... + phi(n);

更多欧拉函数的说明：http://972169909-qq-com.iteye.com/blog/1131309

  
爽