Cod sursa(job #783758)

Utilizator dumytruKana Banana dumytru Data 3 septembrie 2012 20:26:40
Problema Fractii Scor 0
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include<iostream>
using namespace std;


unsigned phi(unsigned long x) {

unsigned ret = 1,i,pow;

for (i = 2; x != 1; i++) {
pow = 1;
while (!(x%i)) {
x /= i;
pow *= i;
}
ret *= (pow - (pow/i));
}
return ret;
}

int main()
{
	long int n,i,z=1;
	cin>>n;
	for(i=2;i<=n;i++)
        z=z+phi(i)*2;
    cout<<z;
    return 0;
}