\[ \boxed { x{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) + \left ( x+a \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 0.012002 (sec), leaf count = 61 \[ \left \{\left \{y(x)\to c_1 e^{-i x} U\left (\frac {1}{2} i (a-i),1,2 i x\right )+c_2 e^{-i x} L_{-\frac {1}{2} i (a-i)}(2 i x)\right \}\right \} \]
Maple: cpu = 0.109 (sec), leaf count = 43 \[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{-ix}}{{\sl M}\left ( {\frac {1}{2}}+{\frac {i}{2}}a,\,1,\,2\,ix\right )}+{\it \_C2}\,{ {\rm e}^{-ix}}{{\sl U}\left ({\frac {1}{2}}+{\frac {i}{2}}a,\,1,\,2\,ix \right )} \right \} \]