Review Safety Stock Target Value. I don't think the requirement is to bring week values. Also it would be great if you don't copy your exact formula on the community. Just rephrase it appropriately we should be able to help you if there are any technical issues
As Safety Stock is maintained in DAT04 Distribution Center Parameters and it has HALFYEAR as time scale, use a function similar to YEARVALUE to populate the half-yearly number in weeks in INV01 module.