1/(1*3)+1/(3*5)+1/(5*7)+...+1/((2n-1)(2n+1))=17/351/2(1-1/3)+1/2(1/升卖备瞎3-1/5)+……+1/2[1/(2n-1)-1/(2n+1)]=17/351-1/3+1/3-1/5+……+1/(2n-1)-1/(2n+1)=34/351-1/(2n+1)=34/351/吵滚逗(2n+1)=1-34/35=1/352n+1=35n=17
