1062D - Fun with Integers - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
long long n;
long long ans;
int main()
{
	cin>>n;
	for(int i=2;i<=n;i++)
		for(int j=i+i;j<=n;j+=i)
			ans+=j/i;
	cout<<ans*4;
	return 0;
}