Extremal polyphase sequences

The unnormalized finite autocorrelation function C(τ) of the sequence A={a_k}ⁿ_k=1 of complex numbers on with the unit circle is defined by C(τ)=Σ^n-τ _k=1a_ka*_k+τ, with C(0)=n, C(-τ)=C*(τ), and |C(n-1)|=1, where z* denotes the complex conjugate of z. We seek the sequence of length n, for each n⩾3, which minimizes the value of max_1⩽τ⩽n-2|C(τ)|, and the value T_n=min_{all sequences} max_1⩽τ⩽n-2 |C(τ)| for this minimizing sequence