gistfile1.py

from math import sqrt

_LOW_PRIMES = (2, 3, 5, 7, 11, 13, 17, 19, 23)

def factors(n):
    # Get the basics out of the way
    # Remove all the low factors in a loop
    for p in _LOW_PRIMES:
        while n % p == 0:
            yield p
            n //= p
    if n == 1:
        return
    isqrt = int(sqrt(n))
    for x in xrange(isqrt, _LOW_PRIMES[-1], -1):
        if n % x == 0:
            for f in factors(x):
                yield f
            for f in factors(n // x):
                yield f
            return
    # Got here: it's prime
    yield n

for i in xrange(1, 65536):
    print "{0} = {1}".format(i, ' * '.join(str(f) for f in factors(i)))