Сумма в факториале

 
(defun fact (n)
   (if (= n 0)
       1
       (* (fact (- n 1)) n)))

(defun fact-sum (n)
  (iter (for i from 1 to n)
        (multiply i into term)
        (summing term)))

CL-USER> (fact-sum 4)
33
CL-USER>

(defun fact-sum (n)
  (loop for i from 1 to n
     for term = 1 then (* i term)
     summing term))

(defun fact (n)
   (if (= n 0) 1 (* (fact (- n 1)) n)))
 
(defun fact+ (n)
  (if (zerop n) 0 (+ (fact+ (1- n)) (fact n))))
 
> (fact+ 4) 
33
> (fact+ 3) 
9

(defun sum-fact (n &optional (s 1) (p 1) (i 1))
  (cond ((> i n) s)
        (t (sum-fact n (+ s (* p i)) (* p i) (+ i 1)))))
 
==> sum-fact
 
(sum-fact 8)
 
==> 46234
 
(sum-fact 100)
 
==> 94269001683709979260859834124473539872070722613982672442938359305624678223479506023400294093599136466986609124347432647622826870038220556442336528920420940314
 
;; можно проверить на калькуляторе...