\[ y''(x)-e^{y(x)}=0 \] ✓ Mathematica : cpu = 0.0667631 (sec), leaf count = 32
\[\left \{\left \{y(x)\to \log \left (-\frac {1}{2} c_1 \text {sech}^2\left (\frac {1}{2} \sqrt {c_1 \left (c_2+x\right ){}^2}\right )\right )\right \}\right \}\]
✓ Maple : cpu = 0.437 (sec), leaf count = 23
\[ \left \{ y \left ( x \right ) =\ln \left ( {\frac {1}{2\,{{\it \_C1}}^{2}} \left ( \left ( \tan \left ( {\frac {{\it \_C2}+x}{2\,{\it \_C1}}} \right ) \right ) ^{2}+1 \right ) } \right ) \right \} \]