The python equivalent:

  real	0m21.891s

On machine in which the C Variant:

  real	0m0.570s

But - I learned about Cython today, so great article.

Interesting that the Python Version takes so much longer.

  import sys

  check=int(sys.argv[1])
  lnum=1
  lcount=1

  for x in range(1,check):
    len=1
    a=x
    while (a>1):
      len+=1
      if a%2==0:
        a=a/2
      else:
        a=(a*3+1)/2
    if len > lcount:
      lcount=len
      lnum=x

  print lcount,lnum