So far, so good.
Take your current result, and:

  1. Add the digits until you get only one digit.
    (i.e.: 64 = 6 + 4 = 10 = 1 + 0 = 1)
     
  2. If the number is less than 5, add five.
    Otherwise, subtract 4.
     
  3. Multiply that result by 2.
     
  4. Subtract 6 from the latest result.

Continue Experiment