An example of a program that contains an algorithm whose Big-Θ is exponential

An example of a program that contains an algorithm whose Big-Θ is exponential. Clearly, explain what n represents in your program. Make some assumption about how long it would take to execute one of the operations that you are counting. Determine how large n would have to be so that the time required would exceed a million years. Is there a more efficient algorithm that will solve the same problem? If so, describe it.