hailstone[n] :=
{
   results = new array

   while n != 1
   {
      results.push[n]
      if n mod 2 == 0    // n is even?
         n = n / 2
      else
         n = (3n + 1)
   }

   results.push[1]
   return results
}

longestLen = 0
longestN = 0
for n = 1 to 100000
{
   seq = hailstone[n]
   if length[seq] > longestLen
   {
      longestLen = length[seq]
      longestN = n
   }
}

println["$longestN has length $longestLen"]