Moving Aggregation

Hi, I am trying to calculate moving backward aggregation for a 4 window length.

| Week     | Original Column    | Aggregation |
| 2022-W46 | 21781.543464000002 | ?           |
| 2022-W47 | 22286.755323999998 | ?           |
| 2022-W48 | 25350.899432       | ?           |
| 2022-W49 | 23805.777280000002 | 93224.9755  |

You can see that when 4 is the window it takes current row and 3 previous rows. I want 4 previous row excluding current row. How to do so?