\[ y''(x)=-\frac {a y(x)}{\left (x^2-1\right )^2} \] ✓ Mathematica : cpu = 0.110455 (sec), leaf count = 67
\[\left \{\left \{y(x)\to \frac {1}{2} \sqrt {1-x^2} e^{-\sqrt {1-a} \tanh ^{-1}(x)} \left (\frac {c_2 e^{2 \sqrt {1-a} \tanh ^{-1}(x)}}{\sqrt {1-a}}+2 c_1\right )\right \}\right \}\]
✓ Maple : cpu = 0.083 (sec), leaf count = 55
\[ \left \{ y \left ( x \right ) =\sqrt {{x}^{2}-1} \left ( \left ( {\frac {x-1}{1+x}} \right ) ^{-{\frac {1}{2}\sqrt {1-a}}}{\it \_C2}+ \left ( {\frac {x-1}{1+x}} \right ) ^{{\frac {1}{2}\sqrt {1-a}}}{\it \_C1} \right ) \right \} \]