\[ \left (1-a^2\right ) x y'(x)+x^3 y^{(3)}(x)+3 x^2 y''(x)=0 \] ✓ Mathematica : cpu = 0.0412251 (sec), leaf count = 29
\[\left \{\left \{y(x)\to \frac {-c_1 x^{-a}+c_2 x^a+a c_3}{a}\right \}\right \}\]
✓ Maple : cpu = 0.017 (sec), leaf count = 18
\[ \left \{ y \left ( x \right ) ={\it \_C1}+{\it \_C2}\,{x}^{a}+{\it \_C3}\,{x}^{-a} \right \} \]