import math

A, B = map(int, input().split())

total = 0
for x in range(A, B + 1):
    if x <= 1:
        continue
    for y in range(2, int(math.sqrt(x)) + 1):
        if x % y == 0:
            break
    else:
        total += (x*x*x) - (x*x) + x + 1

print(total)