\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +y \left ( x \right ) \cos \left ( x \right ) -{{\rm e}^{2\,x}}=0} \]
Mathematica: cpu = 3.134898 (sec), leaf count = 38 \[ \left \{\left \{y(x)\to e^{-\sin (x)} \int _1^x e^{2 K[1]+\sin (K[1])} \, dK[1]+c_1 e^{-\sin (x)}\right \}\right \} \]
Maple: cpu = 0.171 (sec), leaf count = 27 \[ \left \{ y \left ( x \right ) ={{\rm e}^{-\sin \left ( x \right ) }}\int \!{{\rm e}^{2\,x+\sin \left ( x \right ) }}\,{\rm d}x+{{\rm e}^{-\sin \left ( x \right ) }}{\it \_C1} \right \} \]
Sage: cpu = 2.088 (sec), leaf count = 0 \[ \left [{\left (c + \int e^{\left (2 \, x + \sin \left (x\right )\right )}\,{d x}\right )} e^{\left (-\sin \left (x\right )\right )}, \text {\texttt {linear}}\right ] \]