“…When σ u = 0, by the method of J. Ritt [6], Yu Chia-Yung [15], [13] defined the order and type of f (s) under the conditions lim n→+∞ ln |a n | λ n = 0 and lim n→+∞ n λ n < +∞, and obtained some results between the growth of f (s) and the coefficients, which extends some of G. Valiron's results [9]. In this paper, we improve one of his results.…”