Looking for macro to paste same formula in multiple columns with inc rows

Hi -

I am looking for a macro that will paste the same formula in multiple columns with each consequetive column adding one row to the past range (like a lattice tree) for n columns. So copy formula in A1 to B1:B2, the copy B1 to C1:C3, etc for n times. Seems like it should be simple, but I am brand new to VBA. I am in Excel 2007. Any help would be greatly appreciated!