Computations on indices

[Heime]

How can I use 'k-1' in the following function ?

(defun permutor (k word)
  "Generate all permutations of WORD."

  (let ( (wlis '())
         ;; (c (make-vector n 0))
         (i 0) )

    (if (<= k 1)

        (add-to-list 'wlis word)

      (while (< i k)
        (permutor k-1 word)

        (if (evenp i)
            (add-to-list 'wlis (protilus-cswap word i k-1))
          (add-to-list 'wlis (protilus-cswap word 0 k-1)))

        (setq i (1+ i))) )))