McNuggets problem

rosettacode.org/wiki/McNuggets_problem

Calculate (from 0 up to a limit of 100) the largest
non-McNuggets number (a number n which cannot be expressed
with 6x + 9y + 20z = n where x, y and z are natural numbers).

Output:

43


newLISP

(define (cartesian-product lists)
  (if (null? lists)
    '(())
    (let (subproduct (cartesian-product (rest lists)))
      (apply append
        (map
          (fn (x) (map (fn (xs) (cons x xs)) subproduct))
          (first lists))))))

(define (nug? x)
  (let (top 100)
    (exists
      (fn (combo) (= x (apply + combo)))
      (cartesian-product
        (list (sequence 0 top 6)
              (sequence 0 top 9)
              (sequence 0 top 20))))))

(exists (fn (n) (not (nug? n))) (sequence 100 0))
  ===>
43