Search ProblemsRSS Feed
projecteuler.net

Gcd sum

Problem 625 Published on Saturday, 21st April 2018, 04:00 pm; Solved by 218

$G(N)=\sum_{j=1}^N\sum_{i=1}^j \text{gcd}(i,j)$.
You are given: $G(10)=122$.

Find $G(10^{11})$. Give your answer modulo 998244353