1.
If f(0)=0f(0) = 0, f(1)=1f(1) = 1, f(2)=2f(2) = 2, and f(x)=f(x2)+f(x3)f(x) = f(x-2) + f(x-3) for x=3,4,5,x = 3, 4, 5, \ldots, then f(9)f(9) is equal to