Insert formula using Openpyxl

[The Tester Boy]

In python:
I am trying to insert this formula : =@FILTER(CP!$B$5:$B$13,(TDS_Conso_Summary!E2=CP!$A$5:$A$13)*(TDS_Conso_Summary!F2=CP!$C$5:$C$13))

but I am unable to, the code is executed but the excel removes it automatically.

Instead of using @ operator I tried using index, even that didn't work 
Code:

for row in range(2,ws_TDS_Conso_Summary.max_row+1):

formula = f"=INDEX(FILTER(CP!$B$5:$B$13, (TDS_Conso_Summary!E{row}=CP!$A$5:$A$13)*(TDS_Conso_Summary!F{row}=CP!$C$5:$C$13)), 1)"
ws_TDS_Conso_Summary[f'K{row}'] = formula

Error in excel:
Refer attachment