We may note that the Fibonacci and Lucas sequences can be extrapolated backwards using Fn = Fn+2 −Fn+1 and Ln = Ln+2 −Ln+1. Thus, for example, F−1 = 1,F−2 = −1, and so on. Since that the Binet’s formulae remain valid for Fibonacci and Lucas numbers with negative indices, one can deduce the following result (which we shall prove for the sake of completeness)