| 2022 SYSU School Contest |
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| Finished |
This is an easy math problem.
We define a function $$$f(x)$$$ to represent how many pairs of factors $$$(p,q)$$$ of $$$x$$$ satisfy that $$$p$$$ and $$$q$$$ are coprime. When $$$p\not=q$$$ , $$$(p,q)$$$ and $$$(q,p)$$$ are different pairs.
$$$$$$ f(x)=\sum_{p,q|x}[ gcd(p,q)=1 ] $$$$$$
Now we want to calculate
$$$$$$ g(n)=\sum_{i=1}^n f(i) $$$$$$
The answer maybe too large, so you only need to output the result of its modulo of 998244353
A single integer $$$n(1\le n\le 10^{10})$$$
A single integer $$$g(n)$$$
10
48
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