There are two functions that are their own second derivative, and four which are their own fourth derivative.

More precisely there is a 2-dimensional parameter space of functions that are their own second derivative, i.e., any function of the form Ae^x+Be^-x for any constants A and B.

More precisely there is a 2-dimensional parameter space of functions that are their own second derivative, i.e., any function of the form Ae^x+Be^-x for any constants A and B.

Is there a generic form of that for any nth derivative?