\[ \boxed { \left ( {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) \right ) y \left ( x \right ) + \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}-{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) =0} \]
Mathematica: cpu = 0.037505 (sec), leaf count = 40 \[ \left \{\left \{y(x)\to c_1 \left (-W\left (-\frac {e^{-\frac {x}{c_1}-\frac {c_2}{c_1}-1}}{c_1}\right )\right )-c_1\right \}\right \} \]
Maple: cpu = 1.622 (sec), leaf count = 33 \[ \left \{ y \left ( x \right ) =-{\it \_C1}\, \left ( {\it lambertW} \left ( -{\frac {{{\rm e}^{-1}}}{{\it \_C1}} \left ( {{\rm e}^{{\frac { {\it \_C2}}{{\it \_C1}}}}} \right ) ^{-1} \left ( {{\rm e}^{{\frac {x}{{ \it \_C1}}}}} \right ) ^{-1}} \right ) +1 \right ) \right \} \]