\[ y^{(n)}(x)-f\left (\frac {\partial ^{n-2}y(x)}{\partial x^{n-2}}\right )=0 \] ✗ Mathematica : cpu = 0.0030398 (sec), leaf count = 0
DSolve[-f[D[y[x], {x, -2 + n}]] + Derivative[n][y][x] == 0,y[x],x]
, could not solve
DSolve[-f[D[y[x], {x, -2 + n}]] + Derivative[n][y][x] == 0, y[x], x]
✗ Maple : cpu = 0. (sec), leaf count = 0
dsolve(diff(y(x),[x $ n]) = f(diff(y(x),[x $ n-2]))=0,y(x))
, exception
unable to handle ODEs of undefined differential order