Jurjen, this is very nice! -- Like Mark, I'm not sure if this should be in CPython.


Decimal (Python >= 3.3) has sneaked in a couple of fast bignum
algorithms, so calculating and converting the latest Mersenne
prime takes a couple of seconds:

from decimal import *

c = getcontext()
c.prec = MAX_PREC
c.Emax = MAX_EMAX
c.Emin = MIN_EMIN

x = Decimal(2)**74207281 - 1
s = str(x)
assert s[:12] == "300376418084"
assert s[-12:] == "391086436351"