If on transition to the ground state an $\mathrm{H}{\mathrm{e}}^{+}$ ion emits two photons in succession, having wavelengths $1026.7 \stackrel{\circ }{\mathrm{A}}$ and $304 \stackrel{\circ }{\mathrm{A}}$, then the quantum number $n$ corresponding to the exciting state of $\mathrm{H}{\mathrm{e}}^{+}$ ion is [$\mathrm{R}=1.096\times {10}^7 {\mathrm{m}}^{-1}$]