\[ \boxed { \left ( x+3 \right ) {x}^{2}{\frac {{\rm d}^{3}}{{\rm d}{x}^{3}}}y \left ( x \right ) -3\,x \left ( x+2 \right ) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +6\, \left ( 1+x \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -6\,y \left ( x \right ) =0} \]
Mathematica: cpu = 0.030004 (sec), leaf count = 65 \[ \left \{\left \{y(x)\to \frac {1}{4} c_1 \left (x^3-3 x^2+3 x+3\right )+\frac {1}{2} c_2 \left (-x^3+3 x^2-x-1\right )+\frac {1}{8} c_3 \left (3 x^3-5 x^2+x+1\right )\right \}\right \} \]
Maple: cpu = 0.124 (sec), leaf count = 20 \[ \left \{ y \left ( x \right ) ={\it \_C1}\,{x}^{2}+{x}^{3}{\it \_C2}+{ \it \_C3}\, \left ( 1+x \right ) \right \} \]