public class Euler713 {
    public static String solve() {
        long n = 10000000L;
        long total = 0;
        for (long r = 1; r < n; ++r) {
            long q = n / r;
            long s = n - r * q;
            total += (r * q * (q - 1)) / 2 + s * q;
        }
        return Long.toString(total);
    }

    public static void main(String[] args) {
        System.out.println(solve());
    }
}