P16 - Drop every N'th element from a list

lisp

(defun drop (lista n)
  "Drops every N'th element of a list"
    (dropaux lista n 1)
)

(defun dropaux (lista n pos)
  "Drops every N'th element of a list, but looking now at element POS"
    (cond ((eql lista nil) nil)
          ((= (mod pos n) 0) (dropaux (cdr lista) n 1))
          (t (cons (car lista) (dropaux (cdr lista) n (mod (1+ pos) n))))
    )
)