cl-prime-number:factorize-in-prime.lisp

(defun factorize-in-prime (target &key (prime-series *prime-series*))
  (if (eq target 1)
      (return-from factorize-in-prime nil))
  (let ((factor (lcar prime-series)))
    (cons (loop while (= (mod target factor) 0)
             count t
             do (setf target (/ target factor)))
          (factorize-in-prime target :prime-series (lcdr prime-series)))))