One way:

C3: =OFFSET(C3,,-1)+1

In article ,
George wrote:

Simple example:
C3 = B3+1

Insert a new column C; old col C changes to ..
D3 = B3+1 (where col D was col C)

A similar thing occurs if I copy col C, and 'insert copied cells' at
col C. Then, I get ...
C3 = A3+1
D3 = B3+1

What I'd like is to maintain the relative offset ..
C3 = B3+1
D3 = C3+1

Thanks,
George