飓风    方法1    ｛=1+SUM(1/(ROW(1:25)*2))｝

小爪    方法2    ｛=SUM((ROW(1:50)/2=INT(ROW(1:50)/2))*(1/(ROW(1:50))))+1｝

laoyebin 方法3     {=SUMPRODUCT(1/(ROW(1:25)*2))+1}