\[ (1-2 y(x)) y'(x)^2+\left (y(x)^2+1\right ) y''(x)=0 \] ✓ Mathematica : cpu = 0.176411 (sec), leaf count = 46
\[\left \{\left \{y(x)\to \frac {i \left (1-c_1{}^{2 i} (x+c_2){}^{2 i}\right )}{1+c_1{}^{2 i} (x+c_2){}^{2 i}}\right \}\right \}\] ✓ Maple : cpu = 0.256 (sec), leaf count = 11
\[ \left \{ y \left ( x \right ) =\tan \left ( \ln \left ( {\it \_C1}\,x+{\it \_C2} \right ) \right ) \right \} \]