What is the greatest prime factor of 3^6 - 1 ?
Choose the correct choice from the following.
A) 2  B) 3  C) 7  D) 13  E) 17
3^6-1 = (3^3)^2 -1 = (27^2)-1   Dividing (27^2)-1 by 13 will give us a reminder of 0 ( Hint: (2*13+1)^2-1/13 = (Reminder 1)-1=0   Hence the greatest prime factor must be 13.   ANSWER:13
<result>D</result>
What is the greatest prime factor of 3^6 - 1 ?