\[ a \left (a^2-2 b e^{-a x}\right ) y'(x)+a^2 y''(x)+b^2 e^{-2 a x} y(x)=0 \] ✓ Mathematica : cpu = 0.0247021 (sec), leaf count = 50
\[\left \{\left \{y(x)\to c_1 e^{-\frac {b e^{-a x}}{a^2}}-\frac {b c_2 e^{-\frac {b e^{-a x}}{a^2}-a x}}{a^2}\right \}\right \}\] ✓ Maple : cpu = 0.041 (sec), leaf count = 40
\[y \relax (x ) = {\mathrm e}^{-\frac {a^{3} x +2 b \,{\mathrm e}^{-a x}}{2 a^{2}}} \left (\sinh \left (\frac {a x}{2}\right ) c_{1}+\cosh \left (\frac {a x}{2}\right ) c_{2}\right )\]