Title: Commutativityconditionsfordifferentialoperatorsoforders 3,4,5

Abstract: The simplest commutative ring of ordinary differential operators of rank 1 that does not contain the Schrodinger operator is generated by operators of orders 3,4,5. Explicit formulas for Novikov equations describing such a ring are written out. We find a bi-Hamiltonian structure and separation of variavles for these equations.