I know that there are certain techniques and steps on finding expressions for linear and quadratic sequences. But can someone give me a technique or set of steps that I can use to figure out expressions for geometric sequences?

For example, I have the geometric sequence 4,8,16,32,64.... The common ratio is 2. The expression to generate this sequence is 2^n+1. But I would like to learn the steps needed to figure out the expression. Can someone please help.