Date from one cell to weeknum to another cell

[GKE2019]

Hello,

Is it possible to automate the following:?

That the weeknumbers will be put on the right (Collumn F) and get the data from (Collumn E)?

And if there is no text at Collumn E, there will be no text at Collumn F?

[#2]

@GKE2019 

=IF(E2<>"",ISOWEEKNUM(E2),"")

Maybe with this formula which works in my spreadsheet. 

[#3]

When I put it in there I get an Error