Before revision:  It is well known that both the LOG and the EXPn utility functions are connected with the HARA utility function by means of a limiting procedure : in the first case the parameter of a HARA utility function is going to zero and in the second case to infinity.
After revision:  It is well known that the exponential utility function is connected with the HARA utility function by means of a limiting procedure : in the first case the parameter of a HARA utility function is going to zero and in the second case to infinity.