what is best 3d6

import random

def d6():
    return random.randint(1,6)

def roll4d6discard():
    results = [d6() for i in range(4)]
    results.sort()
    return results[1:4]

def roll3d6():
    results = [d6() for i in range(3)]
    return results

def roll3d6reroll():
    results = [d6() for i in range(3)]
    results.sort()
    results[0] = d6()
    return results

def roll3d6rerollones():
    results = [d6() for i in range(3)]
    results.sort()
    while 1 in results:
        results[0] = d6()
        results.sort()
    return results

if __name__ == "__main__":
    n = 10000000
    a3d6only = 0.0
    a3d6onereroll = 0.0
    a4d6discardworst = 0.0
    a3d6rerollallones = 0.0
    for i in range(n):
        a3d6only += sum(roll3d6())
        a3d6onereroll += sum(roll3d6reroll())
        a3d6rerollallones += sum(roll3d6rerollones())
        a4d6discardworst += sum(roll4d6discard())
    a3d6only /= n
    a3d6onereroll /= n
    a4d6discardworst /= n
    a3d6rerollallones /= n
    print "Avergae 3d6 %lf" % (a3d6only)
    print "Avergae 3d6 with one reroll %lf" % (a3d6onereroll)
    print "Avergae 3d6 with all ones rerolled %lf" % (a3d6rerollallones)
    print "Avergae 4d6 %lf" % (a4d6discardworst)