2/(1*3)+｜1/2-1/4｜+2/(3*5)+｜1/4-1/6｜+2/(5*7)+｜1/6-1/8｜.2/(27*29)+｜1/28-1/30｜=（1-1/3+1/3-1/5+1/5-1/7+……+1/27-1/29）+（1/2-1/4+1/4-1/6+1/6-1/8+……+1/28-1/30）=（1-1/29）+（1/2-1/30）=28/29+7/...