How do you find nth term rule for 1,3,9,27,...?

1 Answer
Jan 31, 2017

The n-th term of this sequence appears to be 3^(n-1), n >= 1.

Explanation:

These are powers of 3 ordered from 3^0 = 1 to 3^a (for an integer a >=1). However, the first convenient value for n is 1, not 0 (imagine saying the 0th term of a sequence). Because of that, since the first term is actually 3^0, we need to start from the first term (n=1) being

3^(1-1). The next is 3^(2-1), 3^(3-1) ... 3^(n-1).