The discrete-time Fourier transform of a signal x[n] is X(Ω)=(1+cos Ω)e^-jΩ. Consider that x_p[n] is a periodic signal of period N=5 such that Note that x_p[n]=Σ^N-1_k=0a_ke^j2πkn/N. The magnitude of the Fourier series coefficient a₃ is _______. (Round off to 3 decimal places).