Calculate rent with 15% increase every 3 years

With A1 is starting amount
A2=15%
D1 is starting year,
E1=D1 copy to the right

Rent amount, D2:
=$A$1*(1+INT((COLUMNS($D$1:D1)-1)/3)*$A$2)

copy to the right

Thanks for your quick reply. The years are in 1 column, I replace "columns() to Rows() = $A$1*(1+INT((ROWS($C$4:C4)-1)/3)*$A$2)
It looks fine but the formula is taking 15% of the base year not the previous 3 years

2018-2020 - USD 500
2021-2022 - 15% increase from prev 3 years rent (500 + 15% = 575)
2023-2025 - 575+15% = 661.25

If I understand the setup correctly* then the following should work in cells B4 and down:

Formula:

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*Cell A1 =500
*Cell A2 = 15%
*Cell A4 = 2018
*Cell A13 = 2027
Let us know if you have any questions.