=SUM(OFFSET($C$2,0,0,1,LEFT($A$1,LEN(A1)-1)*1))
＝sum(offset(c3,,,,match(a1,$c$1:$ag$1,)))
=SUM(OFFSET(C3,0,0,1,$A$1))a1需要为数字格式，为空值时显示#REF!
A3=SUM($C$3:INDIRECT(ADDRESS(3,A1+2,4,1),1))
