\[ y''(x)+e^x \sin (y(x))=0 \] ✗ Mathematica : cpu = 1.24883 (sec), leaf count = 0 , could not solve
DSolve[E^x*Sin[y[x]] + Derivative[2][y][x] == 0, y[x], x]
✗ Maple : cpu = 0. (sec), leaf count = 0 , could not solve
dsolve(diff(diff(y(x),x),x)+exp(x)*sin(y(x))=0,y(x))