In this paper, we characterize the complex sequences (zJn which satisfy the following condition: For each complex sequence (an)", there exists a function f such that the functions t z n f ( t ) are LEBESGUE integrable and a,= t z n f ( t ) d t for all neN. In this case, we give for every sequence (a")" infinitely many Cm functions f satisfying some growth conditions in x = O and x = + co, and such that a, = m 0 . m t'"f(t)dt.Finally, we extend this result fo; BANACH space valued functions.