Creating a duplicate of each cell in a column

[alwasl8]

I would like to create a duplicate of each cell in a column and be able to auto fill the pattern on out.

Example:
B1: =A1
B2: =A1
B3: =A2
B4: =A2
B5: =A3
B6: =A3

and on and on.

I cant get the auto fill to continue on with the pattern. It just keeps repeating the existing cell and doesn't increment.

Thanks.

 

[Rick Rothstein]

Try putting this formula in cell B1 and copy it down as to twice the number of rows as there is actual data for...

=INDEX(A:A,1+INT((ROW(A1)-1)/2))