\[ \boxed { {x}^{2}{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) + \left ( x+a \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -y \left ( x \right ) =0} \]
Mathematica: cpu = 0.054507 (sec), leaf count = 37 \[ \left \{\left \{y(x)\to \frac {c_1 (a+x)}{a+1}-\frac {c_2 x e^{a/x}}{a^2 (a+1)}\right \}\right \} \]
Maple: cpu = 0.016 (sec), leaf count = 19 \[ \left \{ y \left ( x \right ) = \left ( x+a \right ) {\it \_C1}+{\it \_C2} \,x{{\rm e}^{{\frac {a}{x}}}} \right \} \]