\[ y^{(n)}(x)-f\left (\frac {\partial ^{n-1}y(x)}{\partial x^{n-1}}\right )=0 \] ✗ Mathematica : cpu = 0.0071698 (sec), leaf count = 0 , could not solve
DSolve[-f[D[y[x], {x, -1 + n}]] + Derivative[n][y][x] == 0, y[x], x]
✗ Maple : cpu = 0. (sec), leaf count = 0 , exception
unable to handle ODEs of undefined differential order