At the end of first six months after the company began giving cell phones to its sale force, it averaged 200 cell minutes per month. For next five years, its monthly cell phone utilize tripled every six months. How many cell minutes per month were being utilized at the end of 4 years? Forecasts general term, or nth term, an, for sequence.
1/6,2/7,3/8,4/9,5/10...