(1/3+1/4……+1/2006)(1/2+1/3……+1/2006)-(1/2+1/3+……+1/2006)(1/3+1/4……+1/2005)

问题描述:

(1/3+1/4……+1/2006)(1/2+1/3……+1/2006)-(1/2+1/3+……+1/2006)(1/3+1/4……+1/2005)