The series converges at and diverges at .

Based on this information we know something about how big and small the radius of convergence of the power series can be. Between what two values must lie?

(Give the possible values as an interval: thus, if can be greater than or equal to 3 but must be less than 8, enter [3,8). If there is no upper or lower bound for , give the value as Inf or -Inf.)