I was trying to solve [this](https://vjudge.net/problem/LightOJ-1370)(LightOJ 1370) problem. When I failed to come up with a memory efficient solution, I looked at some AC solutions.↵
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Interestingly, the solutions used a property that states that the minimum number that has a phi value greater than or equal to a given number, must be the first prime number greater than the given number. For example, For 20, the answer is 23.↵
I am looking for a proof of this property.
↵
Interestingly, the solutions used a property that states that the minimum number that has a phi value greater than or equal to a given number, must be the first prime number greater than the given number. For example, For 20, the answer is 23.↵
I am looking for a proof of this property.