(define (A m n) 
  (cond ((= m 0) (+ n 1))
        ((= m 1) (+ n 2))
        ((= m 2) (+ 3 (* n 2)))
        ((= m 3) (- (expt 2 (+ n 3)) 3))
        ((= n 0) (A (- m 1) 1))
        (else (A (- m 1) (A m (- n 1))))
  )
)