\[ \boxed { {x}^{2} \left ( x-y \left ( x \right ) \right ) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +a \left ( x{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -y \left ( x \right ) \right ) ^{2}=0} \]
Mathematica: cpu = 0.866110 (sec), leaf count = 37 \[ \left \{\left \{y(x)\to x \left (\left ((a-1) \left (\frac {(-1)^{a+1} c_1}{x}-c_2\right )\right ){}^{\frac {1}{1-a}}+1\right )\right \}\right \} \]
Maple: cpu = 1.670 (sec), leaf count = 47 \[ \left \{ {\it \_C1}+ \left ( ax-x \right ) {\it \_C2}-{x}^{a}y \left ( x \right ) \left ( x-y \left ( x \right ) \right ) ^{-a}+{x}^{a+1} \left ( x-y \left ( x \right ) \right ) ^{-a}=0 \right \} \]