The Stern diatomic sequence via generalized Chebyshev polynomials

Let a(n) be the Sterns diatomic sequence, and let x1,...,xr be the distances between successive 1s in the binary expansion of the (odd) positive integer n. We show that a(n) is obtained by evaluating generalized Chebyshev polynomials when the variables are given the values x1+1, ..., xr+1, and we derive a formula expressing the same polynomials in terms of sets of increasing integers of alternating parity. We also show that a(n) = Det(Ir + Mr), where Ir is the rxr identity matrix, and Mr is the rxr matrix that has x1,...,xr along the main diagonal, then all 1s just above and below the main diagonal, and all the other entries are 0.