你的公式5261在哪里4102？右边是我的1653公式：专1/[n(n+1)(n+2)][1/n-2/(n+1)+1/(n+2)]/2 原式(1/2)[(1/1-2/2+1/3)+(1/2-2/3+1/4)+(1/3-2/4+1/5)+(1/4-2/5+1/6)+……属+ (1/17-2/18+1/19)+(1/18-2/19+1/20)+(1/19-2/20+1/21)+(1/20-2/21+1/22)] (1/2)[(1/1+1/2+……+1/20)-2(1/2+1/3+……+1/21)+(1/3+1/4+……+1/21+1/22)] (1/2)[(1/1+1/2)-2(1/2+1/21)+(1/21+1/22)] (1/2)[1/2-1/21+1/22] (1/2)[6/11-1/21] (1/2)[115/231]115/462