An satisfies A1A2 = 1 / 3, A3 = 1 / 9, find the general term formula

An satisfies A1A2 = 1 / 3, A3 = 1 / 9, find the general term formula

Let the common ratio be q, then A2 = A1 * q, A3 = A1 * q ^ 2
And an satisfies A1A2 = 1 / 3, A3 = 1 / 9
So A1 ^ 2 * q = 1 / 3, A1 * q ^ 2 = 1 / 9
By multiplying the two formulas, A1 ^ 3 * q ^ 3 = 1 / 27, A1 * q = 1 / 3 = A2
So A1 = 1
So the general formula an = 1 / 3 ^ (n-1)