#include <bits/stdc++.h>
using namespace std;

int main() {
  int A, B, Ans = 0; cin >> A >> B;
  for (int i = max(A, 2); i <= B; i++) {
    bool prime = true;
    for (int j = 2; j * j <= i; j++)
      if (i % j == 0) prime = false;
    if (prime) Ans += i * i * i - i * i + i + 1;
  }
  cout << Ans << endl;
}