Possible options with f(1)=4: Second and third. Let's check each one: Second option: f(1)=4 n=2→f(2)=5*f(2-1)=5*f(1)=5*4→f(2)=20=f(2) of the table. n=3→f(3)=5*f(3-1)=5*f(2)=5*20→f(3)=100=f(3) of the table.
Third option: f(1)=4 n=2→f(2)=16*f(2-1)=16*f(1)=16*4→f(2)=64 different to 20=f(2) of the table.
Answer: The recursive function that defines the sequence is the second option: f(1)=4, f(n)=5*f(n-1), for n>=2
