t = 1

while t:

    n, k = map(int, input().split())

    ans = 0
    for i in range(n, k + 1):
        d = 2
        f = True
        while d * d <= i:
            if i % d == 0:
                f = False
                break
            d += 1
        
        if(f):
            ans += i**3 - i**2 + i + 1


    print(ans)

    t -= 1