\[ x^3 y''(x)-a \left (x y'(x)-y(x)\right )^2=0 \] ✓ Mathematica : cpu = 0.0686158 (sec), leaf count = 26
DSolve[-(a*(-y[x] + x*Derivative[1][y][x])^2) + x^3*Derivative[2][y][x] == 0,y[x],x]
\[\left \{\left \{y(x)\to -\frac {x \log \left (a \left (-\frac {c_1}{x}-c_2\right )\right )}{a}\right \}\right \}\] ✓ Maple : cpu = 0.885 (sec), leaf count = 23
dsolve(x^3*diff(diff(y(x),x),x)-a*(x*diff(y(x),x)-y(x))^2=0,y(x))
\[y \left (x \right ) = -\frac {\ln \left (\frac {a \left (c_{1} x -c_{2}\right )}{x}\right ) x}{a}\]