luke-2.py

MIN, MAX = 10, 100
primes = [str(prime) for prime 
          in range(MIN, MAX) 
          if all(prime%i != 0 for i in range(2, prime))]

def takeLowest(n, primes):
    for i, prime in enumerate(primes):
        if prime.startswith(n):
            return primes.pop(i)
    raise Exception("No such number exists")

def findn(n, primes):
    result = str(n)
    while len(result) < n:
        result += takeLowest(result[-1], primes)[1]
    return result


print findn(9, primes)