drop down list

[viviantan2018]

Excel Spread sheet:

Column:     a    b    c   d

           row   

             1   xy  21

             2   ts   13

when I key : =a1, it show "xy"

                    =b1, it show "21"

when I drag down list, it will show:

                   =a3

                   =b3

                   =a5

                   =b5

but how can we make it appear as:

                 =a2

                =b2

                =a3

                =b3

                =a4

                =b4

Thanks!

[#2]

If you start from first row, in first cell =A1, in second one

=OFFSET($A$1,INT((ROW()-1)/2),MOD(ROW()-1,2))

and drag it down.

Attached