genmatrix question



Hello, list. I need to create the 4x4 matrix, a upper-left element of 
which has indices [0,0].
The genmatrix(a,3,3,0,0) command gives such matrix, but to call the 
element of this matrix one needs to use indices from 1 to 4.( for 
instance, to call the element "a_00" in example below one needs to type 
"a[1,1];")
Is it possible to create an matrix, the upper-left element of which can 
be called by a[0,0]?


(%i1) a:genmatrix(a,3,3,0,0);
                         [ a      a      a      a     ]
                         [  0, 0   0, 1   0, 2   0, 3 ]
                         [                            ]
                         [ a      a      a      a     ]
                         [  1, 0   1, 1   1, 2   1, 3 ]
(%o1)                   [                            ]
                         [ a      a      a      a     ]
                         [  2, 0   2, 1   2, 2   2, 3 ]
                         [                            ]
                         [ a      a      a      a     ]
                         [  3, 0   3, 1   3, 2   3, 3 ]
(%i2) a[0,0];
apply: no such matrix element: [0, 0]
  -- an error. To debug this try: debugmode(true);
(%i3) a[1,1];
(%o3)                                a
                                       0, 0
(%i4)

P.S. Sorry for my rough english.