已知数列an的前n项和Sn=2n^2+n,则lim[1/a1a2+1/a2a3+1/a3a4+...+1/anan+1]的值为

问题描述:

已知数列an的前n项和Sn=2n^2+n,则lim[1/a1a2+1/a2a3+1/a3a4+...+1/anan+1]的值为