What electronic transition in Li²⁺  produces the radiation of the same wavelength as the first line in the Lyman series of Hydrogen

$$\begin{gathered} \frac{1}{\mathrm{\lambda }}={\mathrm{Rz}}^2\left(\frac{1}{{\mathrm{n}}_1^2}-\frac{1}{{\mathrm{n}}_2^2}\right) \\ \mathrm{for} \mathrm{Li}, \mathrm{z}=3 \\ \frac{1}{\mathrm{\lambda }}=3^2\mathrm{R}\left(\frac{1}{{\mathrm{n}}_1^2}-\frac{1}{{\mathrm{n}}_2^2}\right)---\left(1\right) \\ \mathrm{for} \mathrm{H}, \mathrm{z}=1, \mathrm{first} \mathrm{line} \mathrm{of} \mathrm{Lyman} \mathrm{series} \\ \frac{1}{\mathrm{\lambda }}=\mathrm{R}\left(\frac{1}{1^2}-\frac{1}{2^2}\right)---\left(2\right) \\ \mathrm{By} \left(1\right) \& \left(2\right), \\ {3}^2\mathrm{R}\left(\frac{1}{{\mathrm{n}}_1^2}-\frac{1}{{\mathrm{n}}_2^2}\right)=\mathrm{R}\left(\frac{1}{1^2}-\frac{1}{2^2}\right) \\ \mathrm{first} \mathrm{line} \mathrm{of} \mathrm{Lyman} \mathrm{series} \\ 1\mathrm{st} \mathrm{line} {\mathrm{n}}_1=1 \\ {\mathrm{n}}_2=2 \\ \mathrm{In} {\mathrm{Li}}^{2+} \mathrm{electronic} \mathrm{transition}, \\ 6\mathrm{th} \mathrm{level} \mathrm{is} \mathrm{same} \mathrm{as} 2\mathrm{nd} \mathrm{level} \mathrm{in} \mathrm{H}-\mathrm{atom} \\ \& 3\mathrm{rd} \mathrm{level} \mathrm{as} \mathrm{first}. \\ \mathrm{So}, \mathrm{n}=6 \mathrm{to} \mathrm{n}=3 \end{gathered}$$