P37

(load "p36.l")

(de totient-phi (N)
   (sum  # The spec seems wrong, Euler's function needs '*' instead of '+'
      '((X)  # Better use (apply * (mapcar '((X) ..) (prime-factors-mult N)))
         (*
            (dec (car X))
            (** (car X) (dec (cadr X))) ) )
      (prime-factors-mult N) ) )

http://picolisp.com/wiki/?99p37

10jul10

abu