\[ \boxed { x{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) + \left ( x+a+b \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +ay \left ( x \right ) =0} \]
Mathematica: cpu = 0.035004 (sec), leaf count = 37 \[ \left \{\left \{y(x)\to c_1 e^{-x} U(b,a+b,x)+c_2 e^{-x} L_{-b}^{a+b-1}(x)\right \}\right \} \]
Maple: cpu = 0.062 (sec), leaf count = 29 \[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{-x}}{{\sl M}\left (b ,\,a+b,\,x\right )}+{\it \_C2}\,{{\rm e}^{-x}}{{\sl U}\left (b,\,a+b,\,x \right )} \right \} \]