let 不^{n}=不*不^{n-1}. n>1
so 不^{1}(which is 不) is the base case of the recursive formula.
u have to define/specify the base case first, before u can get the value
of the high order formula.
which means u have to answer the question "为什么不", before u can ask
为什么不不（不^2）.
It let me recall the 子非我 question, it can only be answered if the
子非鱼 is solved.
* here is a general purpose function, please costomized to ur special prupose.
