Auto-fill function

Hello Everyone,
I am currently working an a project that requires a sequence number to auto fill across specific cells. In the workbook attached, column M should auto fill with whatever the seq. # is in column I. The seq. # in column R, should auto fill with whatever the seq # in column M is, so on and so forth. In short, I need the sequence columns to auto-fill with whatever the previous sequence # was. Any suggestions?

Like this?