The first harmonic components of the absorption/dispersion spectrum, the intensity and Boltzmann-Gibbs entropy are investigated within a truncated continued fraction approach for the non-autonomous system of ordinary differential equations modelling a coherently driven 2-level atom bathed in a broadband squeezed vacuum. For the given data, regions of amplification, steep variational dispersion are identified. The Boltzmann-Gibbs entropy shows dense (less dense) oscillatory pattern in the weakly (strongly) driven case. This oscillatory pattern recedes for non-zero atomic detuning.