\[ x^3 y^{(3)}(x)+(x+3) x^2 y''(x)+5 (x-6) x y'(x)+(4 x+30) y(x)=0 \] ✓ Mathematica : cpu = 261.508 (sec), leaf count = 15142
\[ \text {Too large to display} \] ✓ Maple : cpu = 0.332 (sec), leaf count = 188
\[y \relax (x ) = \frac {c_{3} {\mathrm e}^{-x} \left (x^{8}+28 x^{7}+450 x^{6}+5100 x^{5}+42900 x^{4}+267120 x^{3}+1179360 x^{2}+3326400 x +4536000\right ) \Ei \left (1, -x \right )+c_{2} \left (x^{8}+28 x^{7}+450 x^{6}+5100 x^{5}+42900 x^{4}+267120 x^{3}+1179360 x^{2}+3326400 x +4536000\right ) {\mathrm e}^{-x}+60 c_{3} \left (x^{4}-84 x^{3}+2016 x^{2}-20160 x +75600\right ) \ln \relax (x )+c_{3} x^{7}+29 c_{3} x^{6}+480 c_{3} x^{5}+\left (c_{1}+5612 c_{3}\right ) x^{4}+\left (-84 c_{1}+40152 c_{3}\right ) x^{3}+\left (2016 c_{1}+654192 c_{3}\right ) x^{2}+\left (-20160 c_{1}-2761920 c_{3}\right ) x +75600 c_{1}+27367200 c_{3}}{x^{6}}\]