\[ 4 x y''(x)-(a+x) y(x)=0 \] ✓ Mathematica : cpu = 0.074702 (sec), leaf count = 78
\[\left \{\left \{y(x)\to \frac {1}{4} c_2 e^{-x/2} x \, _1F_1\left (\frac {1}{128} (-32 (-a-4 i)-128 i)+1;2;x\right )+\frac {1}{4} c_1 e^{-x/2} x U\left (\frac {1}{128} (-32 (-a-4 i)-128 i)+1,2,x\right )\right \}\right \}\] ✓ Maple : cpu = 0.122 (sec), leaf count = 21
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\sl M}_{-{\frac {a}{4}},\,{\frac {1}{2}}}\left (x\right )}+{\it \_C2}\,{{\sl W}_{-{\frac {a}{4}},\,{\frac {1}{2}}}\left (x\right )} \right \} \]