hello
f(3) = 5
f(4) = 10
f(5) = 15
f(6) = 20
assuming it's an arithmetic progression
common difference = f(4) - f(3) = 10 - 5 = 5
[tex]\begin{gathered} \text{common difference = 10 - 5 = 5} \\ f(n)=f(n-1)\cdot5 \end{gathered}[/tex]the recursive formula for this sequence is f(n) = f(n - 1) * 5
