> > Yeah, I know "cdddddddddddddddddr" isn't "official API".
> `cddddr' is the longest I think ...

(defun cdddddddddddddddddr (list)
  "Return the 17th cdr of LIST."
  (nthcdr 17 list))

or

(defun cdddddddddddddddddr (list)
  "Return the 17th cdr of LIST."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cddddr (cddddr (cddddr (cddddr (cdr list))))))


(setq foo '(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19))
(cdddddddddddddddddr foo)