huntian oy1
---恢复内容开始--- huntian oy 问题类别 杜教筛 算法类别 数论 其他知识点 无 来源 HDU-6706 Problem Description One day, Master oy created a new function to celebrate his becoming a 'huntian' in majsoul. $f(n,a,b)=\sum_{i=1}^n \sum_{j=1}^i gcd(i^a−j^a,i^b−j^b)[gcd(i,j)=1]%(10^9+7)$ Given n, a and b, Master oy wanted Newbie jj who was still a 'chuxin' to answer the value of f(n,a,b). Input There are multiple test cases. The first line contains an integer T, indicating the number of test cases. For each test case, there are three positive integers n, a and b which are separated by spaces. It's guaranteed that a and b are