---
categories: Number theory
---

## Problems
- [GCD Extreme](https://onlinejudge.org/external/114/p11426.pdf) [^2]
- [GCD Extreme](http://www.spoj.com/problems/GCDEX/) (with strict time limit) [^2]
- [Coprime Triples](https://www.codechef.com/LTIME13/problems/COPRIME3) [^3]
- [ReflectiveRectangle](https://community.topcoder.com/stat?c=problem_statement&pm=13217&rd=15859) [^1]

## See also
- [Multiplicative function]()

## External links
- [A Dance with Mobius Function](https://discuss.codechef.com/t/a-dance-with-mobius-function/11315)
- [Möbius inversion formula. Multiplicative Functions](http://web.archive.org/web/20150714124408/http://mathcircle.berkeley.edu/original/Multiplicative.pdf)

[^1]: <https://apps.topcoder.com/wiki/display/tc/SRM+626#ReflectiveRectangle>
[^2]: <https://discuss.codechef.com/t/a-dance-with-mobius-function/11315>
[^3]: <https://discuss.codechef.com/questions/46074/coprime3-editorial>