13. (10 points) Suppose Algorithm X operates on linear arrays. Suppose that if the array has length one, then Algorithm X returns an answer with a con- stant amount of work. Otherwise, Algorithm X calls itself recursively three times on linear arrays that are 2/3 as long, and in doing so performs a lin- ear amount of work creating the subproblems and combining their solutions. That is, the work performed in creating the subproblems and combining their solutions is proportional to the number of elements in the array. Write down a recurrence for the running time of Algorithm X but do not solve it