\[ y''(x)-y'(x)+e^{2 x} y(x)=0 \] ✓ Mathematica : cpu = 0.0120144 (sec), leaf count = 20
\[\left \{\left \{y(x)\to c_2 \sin \left (e^x\right )+c_1 \cos \left (e^x\right )\right \}\right \}\]
✓ Maple : cpu = 0.008 (sec), leaf count = 15
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,\sin \left ( {{\rm e}^{x}} \right ) +{\it \_C2}\,\cos \left ( {{\rm e}^{x}} \right ) \right \} \]