Copy formula down column but need to skip 'n' rows

Hello!

I have been looking around but have been unable how to figure my problem:

I have two workbooks. One workbook serves as a tracker for dates while the other one uses the dates inputted in the first workbook to track futher information based on that date.

When copying this formula I need to 5 rows skipped to pull in the correct - example below:

D6='[662 Foundation Tracking.xls]Spread Footing'!$AR5
D13='[662 Foundation Tracking.xls]Spread Footing'!$AR6
D20='[662 Foundation Tracking.xls]Spread Footing'!$AR6

but instead I am getting:

D6='[662 Foundation Tracking.xls]Spread Footing'!$AR5
D13='[662 Foundation Tracking.xls]Spread Footing'!$AR12
D20='[662 Foundation Tracking.xls]Spread Footing'!$AR19

Does anyone have idea on how to fix this?

Thanks for any help.