(defun remove-char (lst string)
  (cond ((not lst) string)
        ('t (remove-char (cdr lst)
                         (remove (car lst)
                                 string)))))

(defmacro english-reduced (n)
  `(length (remove-char (list #\- #\space)
                        (format nil "~r" ,n))))

(defmacro english-and (n)
  `(cond
     ((= (mod n 100) 0) (english-reduced ,n))
     ((> ,n 100) (+ 3 (english-reduced ,n)))
     ('t (english-reduced ,n))))

(defun e17 ()
  (labels ((e17-iter (n acc)
             (cond ((<= n 0) acc)
                   ('t (e17-iter (- n 1)
                                 (+ acc
                                    (english-and n)))
                       ))))
    (e17-iter 1000 0)))

CL-USER> (e17)
21124

— Me@2023-10-26 06:36:38 PM

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2023.10.26 Thursday (c) All rights reserved by ACHK