\[ f(x) \left (x^2 y''(x)-2 x y'(x)+2 y(x)\right )+y^{(3)}(x)=0 \] ✓ Mathematica : cpu = 0.135757 (sec), leaf count = 88
\[\left \{\left \{y(x)\to c_3 x \left (\int _1^x\frac {\exp \left (-\int _1^{K[2]}f(K[1]) K[1]^2dK[1]\right )}{K[2]^2}dK[2]-x \int _1^x\frac {\exp \left (-\int _1^{K[3]}f(K[1]) K[1]^2dK[1]\right )}{K[3]^3}dK[3]\right )+c_2 x^2+c_1 x\right \}\right \}\] ✓ Maple : cpu = 0.159 (sec), leaf count = 33
\[\left \{y \left (x \right ) = \left (c_{3}+\int \left (c_{2} \left (\int {\mathrm e}^{-\left (\int \left (x^{2} f \left (x \right )+\frac {3}{x}\right )d x \right )}d x \right )+c_{1}\right )d x \right ) x\right \}\]