def f(x):
    return x**3 - x**2 + x + 1
def get_primes(size=10**7):
    is_prime = [True] * (size + 1)
    is_prime[0] = is_prime[1] = False
    primes = []
    for i in range(size + 1):
        if not is_prime[i]:
            continue
        primes.append(i)
        j = 2
        while i * j <= size:
            is_prime[i * j] = False
            j += 1
    return primes
ans = 0
a, b = map(int, input().split())
if b > 1:
    for p in get_primes(b):
        ans += f(p)
if a > 1:
    for p in get_primes(a - 1):
        ans -= f(p)
print(ans)