应该是1\2+5\6+11\12+19\20+.....9899\9900吧?那就是=1-1\2+1-1\6+1-1\12+1-1\20+......1-1\9900 =99-(-1\2+1\2-1\3+1\3-1\4+1\4-1\5+......+1\99-1\100) =99+1\100 =9901\100
你确定不是1\2+5\6+11\12+19\20+.....9899\9900吗?