I want to copy a relative formula from cell A1 to cells A3, A5, A7,.... A3001.

In previous verisons I could highlight A1..A3000 select copy then go to A3
and select paste, and it would work. It would copy A1 to A3, then A2 to A4,
then A3 to a5, all the way down to a3001. This no longer works. How can I
quickly do this?