any payment or series of payments by an employer to an employee or any of his dependents which is paid—

(A) upon or after the termination of an employee’s employment relationship because of (i) death, or (ii) retirement for disability, and

(B) under a plan established by the employer which makes provision for his employees generally or a class or classes of his employees (or for such employees or class or classes of employees and their dependents),

other than any such payment or series of payments which would have been paid if the employee’s employment relationship had not been so terminated;