prime danish phone numbers

import re

#gen_primes is modified from http://stackoverflow.com/a/568618/203705
def gen_primes(start, end):

    # Maps composites to primes witnessing their compositeness.
    # This is memory efficient, as the sieve is not "run forward"
    # indefinitely, but only as long as required by the current
    # number being tested.
    #
    D = {}

    # The running integer that's checked for primeness
    q = 2
    primes = []

    while q != end:
        if q not in D:
            # q is a new prime.
            # Yield it and mark its first multiple that isn't
            # already marked in previous iterations
            #
            if q >= start:
                primes.append(q)
            D[q * q] = [q]
        else:
            # q is composite. D[q] is the list of primes that
            # divide it. Since we've reached q, we no longer
            # need it in the map, but we'll mark the next
            # multiples of its witnesses to prepare for larger
            # numbers
            #
            for p in D[q]:
                D.setdefault(p + q, []).append(p)
            del D[q]

        q += 1
    return primes

def get_danish_nums(name):
    nums = {}
    with open(name, 'r') as f:
        lines = f.readlines()

    for line in lines:
        vals = line.split(',')
        if vals[2].strip() != 'Reserve / Reserve':
            if len(vals[0].strip()) == 8:
                start = int(re.sub(r'[a-z]','0',vals[0]))
                end = int(re.sub(r'[a-z]','9',vals[0]))
                if start == end:
                    nums[start] = True
                else:
                    for num in range(start, end+1):
                        nums[num] = True
    return nums


if __name__ == '__main__':
    print("Getting nums...")
    #CSV built from spreadsheet found here:
    #http://www.erhvervsstyrelsen.dk/numbering_lists
    nums = get_danish_nums('danish_numberlist.csv')
    start = min(nums)
    end = max(nums)

    print("Getting primes...")
    primes = gen_primes(start,end)
    i = 0
    print("Checking...")
    for prime in primes:
        if nums.get(prime, False):
            print("%s is valid prime phone number!" % prime)
            i+=1
    print("%s of %s valid danish phone numbers are prime." % (i, len(nums)))