Depending on your formula (it's always a good idea to post a copy
here), you can make use of:

COLUMN(B1)

instead of 2, if you want to return data from the second column. As
you copy this across, this changes to COLUMN(C1), COLUMN(D1) etc, thus
returning 3, 4, 5 etc and so automatically increments the
col_index_num.

Hope this helps.

Pete