For the sequence 1, 7, 25, 79, 241, 727 … simple formula for {an} is ____________
Explanation: The ratio of consecutive numbers is close to 3. Comparing these terms with the sequence of {3n} which is 3, 9, 27 …. Comparing these terms with the corresponding terms of sequence {3n} and the nth term is 2 less than the corresponding power of 3.