where Fn denotes the Fibonacci numbers. Thus,
a(n) and b(n) almost behave like the “multiplicative Fibonacci sequences” studied in [3].
Remembering that the number of vertices of the n-th Fibonacci tree is exactly Vn = Fn+2 − 1,
we see that the Fibonacci number of the n-th Fibonacci tree is asymptotically
Remark: We can easily modify the construction of Fibonacci trees in the following way: the subtrees of the k-ary analogue of order n are the trees of order n − 1, n − 2, . . . , n − k. Then, the corresponding system of recurrences for the Fibonacci numbers of these trees has exactly the form (1).