Create a new Column using 50% of the row before plus the actual row

Hi Knimers!

I'm trying to create a new column using another column as reference.

The task is to create a kind of "moving average" using 50% of the row before my actual row plus my actual row but not considering this math for the first row of data.

Here is a simple example:

Column A     New Column            Explanation of the task

10                        10                         (Dont consider the math)

20                         25                        (50% of 10 +20)

50                         63                         (50% of 25 +50)

15                         46                          (50% of 63 +46)

Any help?

Tks