An excited ${\mathrm{H}\mathrm{e}}^{+}$ ion emits two photons in succession, with wavelengths $108.5 \mathrm{n}\mathrm{m}$ and $30.4\mathrm{ }\mathrm{n}\mathrm{m}$ in making a transition to the ground state. The quantum number $\mathrm{n}$, corresponding to its initial excited state is



(for a photon of wavelength $\mathrm{\lambda }$, energy $\mathrm{E}=\frac{1240 \mathrm{eV}}{\mathrm{\lambda }\left(\mathrm{in}\mathrm{ }\mathrm{nm}\right)}$)