Complex Vector Computations

I'm not completely comfortable with the OFFSET function or the PRODUCTSUM function and I have been trying to figure out (with no luck) how to do the calculations in the attached spreadsheet. I have to do the calculations for a total of 360 rows down and therefore 360 columns across, so I thought it would be more straightforward to use the aforementioned functions.I tried to make it as straight forward as possible. Let me know if you have any questions. Thanks.