Сумма цифр факториала числа

(defun sum-fact-dgts (n)
  (loop for a in (int-digits n) sum (factorial a)))
 
(defun int-digits (n &optional ac)
  (if (zerop n) ac
      (int-digits (truncate n 10) (cons (rem n 10) ac))))
 
(defun factorial (n &optional (ac 1))
  (if (plusp n) (factorial (1- n) (* ac n)) ac))
 
> (sum-fact-dgts 897)
408240

(defun factorial (n)
   (if (zerop n) 1 (* (factorial (1- n)) n)))
 
(defun factorial+ (n)
  (if (zerop n) 0 (+ (factorial+ (1- n)) (factorial n))))
 
> (factorial+ 4) 
33

(defun factorial+ (n)
  (loop for a from 1 to n
        for m = a then (* a m) sum m))
 
> (factorial+ 4) 
33

(defun sum-fact (n)
  (apply '+ (explode (apply '* (range 2 n)))))
 
==> SUM-FACT
 
(sum-fact 5)
==> 3
 
(sum-fact 10)
==> 27
 
(sum-fact 100)
==> 648

(defun sum-fact-dgts (n)
  (reduce #'+ (int-digits (factorial n))))
 
(defun int-digits (n &optional ac)
  (if (zerop n) ac
      (int-digits (truncate n 10) (cons (rem n 10) ac))))
 
(defun factorial (n &optional (ac 1))
  (if (plusp n) (factorial (1- n) (* ac n)) ac))
 
> (sum-fact-dgts 100)
648
> (sum-fact-dgts 11)
36