The b_n values (left) and ﹩{b}_{n}{\beta }_{n}﹩ values (right) for the hydrogenic approximation at ﹩{T}_{e}={10}^{4}\,\mathrm{and}\,{10}^{2}\,{\rm{K}}﹩ (upper and lower panels, respectively) for different densities (N_e, color scale). The departure coefficients obtained using the nl method show a “bump” at low n levels. The strength and position of the “bump” depend on the physical conditions. As density increases, the l-changing collisions redistribute the electron population more effectively.