Determine whether each of these proposed definitions is a valid recursive definition of a function f from the set of nonnegative integers to the set of integers. if f is not well defined state reason; If f is well defined, find a formula for f(n) when n is a nonnegative integer.
f(0) =1,
f(1)=0,
f(n) = 2f(n-2) for n >= 2