/* cmd /V:ON
	SetEnv.Cmd /Vista /Release
	cl "$F" /EHsc
*/
#include <cstdlib> // abs, _countof
#include <algorithm> // fill
#include <iostream> // cout, endl

const int Limit = 1000000;
static int pfs[1+Limit];

int main()
{
	std::fill(pfs, pfs+_countof(pfs), 1);
	long long count = 1LL * Limit*(Limit+1)/2 - 1;
	for(int d = 2; d <= Limit; ++d) {
		if(pfs[d] == 1) {
			for(int i = d; i <= Limit; i += d) {
				pfs[i] *= -d;
			}
		}
		if(std::abs(pfs[d]) == d) {
			count += 1LL * pfs[d]/std::abs(pfs[d]) * (Limit/d)*(Limit/d+1)/2;
		}
	}
	std::cout << count << std::endl;
	return 0;
}