Puzzle 5

Profiting from my overwrought example 3

from bf7 import *
from sys import argv

if __name__ == "__main__":
    if len(argv) == 1:
        upto = 10
    else:
        upto = int(argv[1]) 
    allprimes = primesupto(upto)

    result = 1
    for prime in allprimes:
        factor = prime
        while factor < upto:
            result *= prime
            factor *= prime
    print result

For me it would have been less work to just write

print 2 * 2 * 2 * 2 * 3 * 3 * 5 * 7 * 11 * 13 * 17 * 19

Best solution, for those who can remember grade school:

def gcd(a, b):
 while(b != 0):
  a, b = b, a%b
 return a
 
def lcm(a,b):
 return a * b / gcd(a, b)
 
print reduce(lcm, range(2, 21))