Function f is an exponential function.
x −1 1 3 5 7
f(x) 14 4 64 1024 16,234
We use exponential function y =ab^x
We find out factor b
When x=1 then y=4, so equation becomes

When x=3 then y=64, so equation becomes

Divide the second equation by first equation

16 = b^2
Take square root on both sides
So b = +-4
f(x) is increasing, so b= 4
Answer is 4