[BZOJ4407]于神之怒加强版

Description:

求$ \sum_{i=1}^{n} \sum_{j=1}^m gcd(i,j)^k $

Hint:

\(n,m<=5*10^6,数据组数<=2000\)

Solution:

显然
\(Ans=\sum_{T=1}^{min(n,m)} \lfloor \frac{n}{T} \rfloor \lfloor \frac{m}{T} \rfloor \sum_{d|T} d^k*\mu(d)\)

标签：lfloor,神之怒,frac,加强版,sum,rfloor,BZOJ4407,gcd
来源： https://www.cnblogs.com/list1/p/10383208.html