\[ \boxed { \left ( \left ( y \left ( x \right ) \right ) ^{2}+1 \right ) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) -3\,y \left ( x \right ) \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}=0} \]
Mathematica: cpu = 0.088011 (sec), leaf count = 93 \[ \left \{\left \{y(x)\to -\frac {i c_1 \left (c_2+x\right )}{\sqrt {c_1^2 x^2+2 c_2 c_1^2 x+c_2^2 c_1^2-1}}\right \},\left \{y(x)\to \frac {i c_1 \left (c_2+x\right )}{\sqrt {c_1^2 x^2+2 c_2 c_1^2 x+c_2^2 c_1^2-1}}\right \}\right \} \]
Maple: cpu = 1.638 (sec), leaf count = 56 \[ \left \{ y \left ( x \right ) ={\it \_C1}\,x\sqrt {- \left ( {{\it \_C1}} ^{2}{x}^{2}+2\,{\it \_C1}\,{\it \_C2}\,x+{{\it \_C2}}^{2}-1 \right ) ^{ -1}}+{\it \_C2}\,\sqrt {- \left ( {{\it \_C1}}^{2}{x}^{2}+2\,{\it \_C1} \,{\it \_C2}\,x+{{\it \_C2}}^{2}-1 \right ) ^{-1}} \right \} \]