观察5/3,7/5,9/7,11/9,13/11……的规律,第n个数为大神们帮帮忙

问题描述:

观察5/3,7/5,9/7,11/9,13/11……的规律,第n个数为大神们帮帮忙

(2n+3)/(2n+1)