(define (f n)
  (if (< n 3)
      n
      (+ (f (- n 1))
         (* 2 (f (- n 2)))
         (* 3 (f (- n 3))))))

(define (g n)
  (if (< n 3)
      n
      (g-helper n)))

(define (g-helper n)
  (if (< n 3)
      2
      (+ (basemaker 0 1 (- n 1))
         (g-helper (- n 1))
         (* 2 (basemaker 0 2 (- n 2))
            (g-helper (- n 2)))
         (* 3 (basemaker 0 3 (- n 3))
            (g-helper (- n 3))))))

(define (basemaker counter constant n)
  (cond ((= 2 n) 2)
        ((= 1 n) 1)
        ((= 0 n) 0)
        (else
            (basemaker (+ counter constant) constant (- n constant)))))

> (f 3)
4
> (f 4)
11
> (f 5)
25
> (g 3)
8
> (g 4)
24
> (g 5)
54