VBA Code To Autofill Formula In Every Nth Row

I have a worksheet wherein Data is in Column A to O.

Column P is just (blank) used as Seperator.

Column Q, and Column R is Output column, where I need Formula in every 4th ROW, Sample formula given in Cell Q4, and Cell R4.

These formula uses relative reference, and not absolute, which i want to fill in every 4th row next to it (starting from Q4,R4), like next Q8,R8, Q12,R12, and so on till end of worksheet, corresponding to data available in Column A, which currently has 144 rows.

(Code should fill in the formula in every 4th Row in Column Q, and Column R starting from Q4, and R4)

Data rows could vary between 200 to 20000, on several days, so use, Column A to find data in last row, and accordingly (using XLDOWN / XLUP) function above formula is required to be autofilled in till end.

My excel version is Excel 2007, but i am giving this sample workbook in 2003 format, which should not be a big issue, I guess!

Thanks

Through the help of Admin, Excel Fox, I am now able to fix this issue. Thank you very much. This thread can be closed/ considered as solved.