Andre numbers are defined, and the simple method of proving gear permutation recursion formula is also given in this paper, by means of the relation between Eular numbers and Dai Xu numbers.

• 用齿排列定义了安德烈数A_n，并用欧拉数En和戴煦数D的关系式，给出了齿排列遍推公式简捷的新证法。