Valery A.Yumaguzhin,

Contact classification of linear ordinary differential equations. II.

It is well-known that any linear ordinary differential equation 
can be transformed to the form 
$$
  y^{(n)}=\sum_{i=2}^na_{n-i}(x)y^{(n-i)}
$$
by a point transformation of variables. 

In this work, we give the classification of $n\geq 3$ order linear 
ordinary differential equations of this form in a neighborhood of a 
regular point up to a contact transformation.