def calculate_mersenne_primes():
    """ Returns all the mersenne primes with less than 500 digits.
        All primes:
        3, 7, 31, 127, 8191, 131071, 524287, 2147483647L, 2305843009213693951L,
        618970019642690137449562111L, 162259276829213363391578010288127L,
        170141183460469231731687303715884105727L,
        68647976601306097149...12574028291115057151L, (157 digits)
        53113799281676709868...70835393219031728127L, (183 digits)
        10407932194664399081...20710555703168729087L, (386 digits)
    """
    mersenne_prime_exponents = [2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 
        127, 521, 607, 1279]
    primes = []
    for exp in mersenne_prime_exponents:
        prime = 1
        for i in range(exp):
            prime *= 2
        prime -= 1
        primes.append(prime)
    return primes
