A new lower bound for a rational approximation on the positive real axis

摘要

Erdos and Reddy (Adv. Math. 21 (1976) 78) estimated the lower bound in question to be 2.75~(-1), but their proof was incorrect. We obtain the optimal bound e~(-1). It is interesting to remark that 2.75~(-1) is very close to e~(-1).