16. A ternary string is a sequence of 0's, 1's and 2's. Just like a bit string, but with three symbols. Let's call a ternary string good provided it never contains a 2 followed immediately by a 0. Let G be the number of good strings of length n. For example, G₁ = 3, and G₂ = 8 (since of the 9 ternary strings of length 2, only one is not good).