Rolling 12 month Absences

Hello stairali and Welcome to Excel Forum.
Tim is asking you to manually put values in column E so that we may attempt to write formulas and/or code to automate the process. I am guessing that those values should be 2,3,5,22,30 and 35.
To that end I modified Tim's array entered formula* so that it reads: =SUM(IFERROR(($B$3:$B3-IF($A$3:$A3<$D3,$D3,$A$3:$A3))^0.5,)^2)
Let us know if you have any questions.