(require 'cl)
(require 'calc-ext)
(defvar calc-command-flags nil)
(defun hash-to-alist (hash)
(let (alist)
(maphash #'(lambda (key val) (push (cons key val) alist)) hash)
alist ))
(defun find-factor (num)
(catch 'found
(let ((i 2))
(while (math-lessp (math-sub i 1) (math-floor (math-sqrt num)))
(if (math-equal (math-mod num i) 0)
(throw 'found i)
(setq i (math-add i 1))) ))))
(defun factorize (num)
(if (= num 1) nil
(let ((p-table (make-hash-table)) p val)
(while (setq p (find-factor num))
(setq num (/ num p))
(if (setq val (gethash p p-table))
(puthash p (1+ val) p-table)
(puthash p 1 p-table) ))
(if (setq val (gethash num p-table))
(puthash num (1+ val) p-table)
(puthash num 1 p-table) )
(hash-to-alist p-table) )))
(defun divisor-sum (num)
(let ((prime-alist (factorize num)) (rst 1))
(while prime-alist
(let* ((pair (car prime-alist)) (p (car pair)) (n (cdr pair)) (sum 0))
(dotimes (i (1+ n))
(setq sum (+ (math-pow p i) sum)) )
(setq prime-alist (cdr prime-alist))
(setq rst (* rst sum)) ))
(- rst num) ))
(defun amicable (num)
(let ((candidate (divisor-sum num)))
(if (and (not (eq candidate num)) (eq num (divisor-sum candidate)))
candidate) ))
(let ((i 1) (tmp 0) (sum 0))
(while (<= i (string-to-number (car argv)))
(if (setq tmp (amicable i))
(setq sum (+ sum tmp)) )
(setq i (1+ i)))
(princ (math-format-value sum))
(princ "\n") )
