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标题: Prep-ps-37 [打印本页]

作者: uruk    时间: 2010-6-17 14:29     标题: Prep-ps-37

本帖最后由 uruk 于 2010-6-17 14:31 编辑

The function f is defined for all integers n by the following rule: f(n) is the number of positive integers each of which is less than n and has no positive factor in common which n other than 1.  If p is any prime number then f(p)=
(1)p-1  (2)p-2  (3)(p+1)/2  (4)(p-1)/2  (5)2

可以告诉我要怎么代换吗??
作者: s    时间: 2010-6-17 17:21

f(n)其实就是与n互质并且小于n的正整数,也就是所有小于n,并且和n的最大公约数是1的正整数。If n is a prime number, then every positive integer less than n has a common factor of 1. 所以总共有n-1个这样的数,f(n)=n-1




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