The function f is defined for all positive integers n by the following rule: f[n] is the number of positive integers each of which is less than n other than 1. If f is any prime number, the f[p] = A. P-1 B. P+1 C. (P-1)/2 D. (P+1)/2 E. 2 ANSWER : A 看不懂题目中间定义f[n]的那句话,我打了下划线的, 请教解题思路,谢谢 |