\[ 4 y''(x)-\left (a+x^2\right ) y(x)=0 \] ✓ Mathematica : cpu = 0.00979663 (sec), leaf count = 36
\[\left \{\left \{y(x)\to c_1 D_{\frac {1}{4} (-a-2)}(x)+c_2 D_{\frac {a-2}{4}}(i x)\right \}\right \}\]
✓ Maple : cpu = 0.103 (sec), leaf count = 33
\[ \left \{ y \left ( x \right ) ={1 \left ( {\it \_C2}\,{{\sl W}_{-{\frac {a}{8}},\,{\frac {1}{4}}}\left ({\frac {{x}^{2}}{2}}\right )}+{\it \_C1}\,{{\sl M}_{-{\frac {a}{8}},\,{\frac {1}{4}}}\left ({\frac {{x}^{2}}{2}}\right )} \right ) {\frac {1}{\sqrt {x}}}} \right \} \]