\[ \boxed { \left ( {a}^{2}{x}^{2}-1 \right ) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +2\,{a}^{2}x{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) =0} \]
Mathematica: cpu = 0.014002 (sec), leaf count = 19 \[ \left \{\left \{y(x)\to c_2-\frac {c_1 \tanh ^{-1}(a x)}{a}\right \}\right \} \]
Maple: cpu = 0.016 (sec), leaf count = 31 \[ \left \{ y \left ( x \right ) ={\it \_C1}+ \left ( {\frac {\ln \left ( ax -1 \right ) }{2\,a}}-{\frac {\ln \left ( ax+1 \right ) }{2\,a}} \right ) {\it \_C2} \right \} \]