\[ y''(x)=-\left (n^2-a^2\right ) y(x)-2 n \coth (x) y'(x) \] ✓ Mathematica : cpu = 0.640471 (sec), leaf count = 273
\[\left \{\left \{y(x)\to \frac {c_2 (-1)^{\frac {1}{2} (-2 n-1)+1} \tanh ^2(x)^{\frac {1}{4} (-2 n-1)+1} \left (\tanh ^2(x)-1\right )^{\frac {1}{2} \left (\frac {a+n}{2}+\frac {1}{2} (a+n+1)+\frac {1}{2} (-2 n-1)+1\right )} \, _2F_1\left (\frac {1}{2} (-2 n-1)+\frac {a+n}{2}+1,\frac {1}{2} (-2 n-1)+\frac {1}{2} (a+n+1)+1;\frac {1}{2} (-2 n-1)+2;\tanh ^2(x)\right ) \exp \left (\frac {1}{2} (n-1) \log \left (1-\tanh ^2(x)\right )-n \log (\tanh (x))\right )}{\sqrt {\tanh (x)}}+\frac {c_1 \tanh ^2(x)^{\frac {1}{4} (2 n+1)} \left (\tanh ^2(x)-1\right )^{\frac {1}{2} \left (\frac {a+n}{2}+\frac {1}{2} (a+n+1)+\frac {1}{2} (-2 n-1)+1\right )} \, _2F_1\left (\frac {a+n}{2},\frac {1}{2} (a+n+1);\frac {1}{2} (2 n+1);\tanh ^2(x)\right ) \exp \left (\frac {1}{2} (n-1) \log \left (1-\tanh ^2(x)\right )-n \log (\tanh (x))\right )}{\sqrt {\tanh (x)}}\right \}\right \}\] ✓ Maple : cpu = 0.595 (sec), leaf count = 36
\[ \left \{ y \left ( x \right ) = \left ( \sinh \left ( x \right ) \right ) ^{-n+{\frac {1}{2}}} \left ( {\it LegendreQ} \left ( a-{\frac {1}{2}},n-{\frac {1}{2}},\cosh \left ( x \right ) \right ) {\it \_C2}+{\it LegendreP} \left ( a-{\frac {1}{2}},n-{\frac {1}{2}},\cosh \left ( x \right ) \right ) {\it \_C1} \right ) \right \} \]