It is stipulated that an operation on positive integer n, whose rule is: F (n) = 3N + 1 (n is odd) 2n − 1 (n is even), then f (3)=______ ,f[f(1)]=______ .

It is stipulated that an operation on positive integer n, whose rule is: F (n) = 3N + 1 (n is odd) 2n − 1 (n is even), then f (3)=______ ,f[f(1)]=______ .

In F (3), n = 3 is an odd number, | f (3) = 3N + 1 = 3 × 3 + 1 = 10; in F [f (1)], first find the value of F (1), ∵ n = 1 is an odd number, | f (1) = 3N + 1 = 3 × 1 + 1 = 4, | f [f (1)] = f (4), in F (4),