If the "A" is really as predictable as you implied in your comment to Ruger28 (and not general as I assumed in my Answer), and you want a vectorized way to do it, you can use reshape:
numIterations = 5;
result = reshape([1 : numIterations*4]', 4, [])'
You get:
result =
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
17 18 19 20
Of course, this vectorized version is the more MATLAB-y way to do it. No for loops are needed at all. (This way also uses your preferred and better variable name of "result".)