I would like to know if it possible in Maple 12 to efficiently compute recursive procedures with two variables.

A simple example would be: f(a,0):=1 for all a>=0, f(0,b):=1 for all b >=0 and f(a,b) :=f(a-1,b) + f(a,b-1) for

a>0, b>0 (which defines the binomial coefficients). In trying to do this in a straightforward way i get

the error message "too many levels of recursion". Using 'trace' I see that Maple doesn't seem to be

creating a remember table for functions of two variables. Am I missing something?