Looping through cells setting a formula

I have sorted the reference to the cell I want the formula in. I now have a problem of how to refer to a cell in a different excel workbook (using UNC path).

I am trying to use

For i = 5 To 10
For j = 2 To 26
Sheets("Infections").Cells(i, j).Formula = "='\\svr-filer01\group$\Weekly Management Reporting\Ward Governance Reporting\09-10\[Data Input.xls]Infections'!" & j & (inf + i - 5)
Next j
Next i

I know the highlighted J is incorrect. How do I refer to a cell in a formula using R1C1?

Jonathan