Calculate week

I would like to rename:
<Filname> <year> <week>

Iknow that there are several Ways in the world to calculate the number of the week. e.g. 1 january week can be 52 or 1 . Or the week starts Monday or sunday..

If you would do one version of calculate, I could change with Plus 1 or minus 1 to my regional wished solution.

Thank you
Gerhard

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