Removing all duplicate integers and sublists from a list

Question

I am trying to write a function that removes all duplicate integers and sublists from a list input. My current code is as follows:

(define (nested-reduce lst)
  (cond
    [(empty? lst) '()]
    [(member (car lst) (cdr lst)) (cons (car lst) (nested-reduce (remove (car lst) (cdr lst))))]
    ;[lst] ;check lst status
    [(list? (car lst))
     (letrec ([search-and-reduce
               (lambda (x)
                 (cond
                   [(empty? x) '()]
                   [(member (car x) (cdr x)) (cons (car lst) (search-and-reduce (remove (car lst) (cdr lst))))]
                   )
                 )])
       (search-and-reduce (car lst)))
     ]
    )
  )

(nested-reduce '(1 3 (2 5) (2 5) (2 5 (2 5) (2 5)) 3 7 1)) ;should return (1 3 (2 5) (2 5 (2 5)) 7).

When I run it, I get '(1 3 (2 5) . #<void>). What should I do? Please reply at your earliest convenience.