auto fill function or formula

Hello,
Please see attached excel sheet. I need to auto fill the blank spaces on column A with the previous value. So for example, I need to fill A2-A3 with the value of A1 (i.e. 9) and A6:A17 wwith teh value of A5 (ie 13) and so on until the end of the column.
Is there a formula that can do this?
Thanks!