#| BEGIN (Write your solution here) |#
(define (cont-frac n d k)
  (define (iter n d k res)
    (if (= k 0)
        res
        (iter n d (- k 1) (/ (n k) (+ (d k) res)))))
  (iter n d k 0))

(define (e k)
  (+ 2 (cont-frac (lambda (i) 1)
             (lambda (i) (if (= (modulo i 3) 2)
                             (* 2 (+ 1 (quotient i 3)))
                             1.0))
             k)))
#| END |#