brihat

     proc main(max_a0: int): int =
       var a, longest, len, max_len : int
     
       for a0 in countup(1, max_a0):
         a = a0
         len = 0
     
         while a != 1:
           len += 1
           if (a mod 2 != 0): a = (3*a + 1)
           a = a div 2
     
         if len > max_len:
           max_len = len
           longest = a0
     
       return longest
     
     # Main program starts here
     echo(main(1000000))

    Python 3.3.2+ (default, Oct  9 2013, 14:50:09) 
    [GCC 4.8.1] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> noel="noël"
    >>> noel[::-1]       # reverse
    'lëon'
    >>> noel[0:3]        # first three characters 
    'noë'
    >>> len(noel)        # length
    4