Contact us
Choose a category below so we can get back to you as quickly as possible.
數列公式:(2n-1)cosnπn為正整數,pi代表 第二十個是-39 第n個:若n為偶數,則為-(2n-1);n為奇數,則為(2n-1)
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.