Boy, I really suck at this. One more try assuming strings of length 2-4:

length of 2: 5 . 4 = 20
length of 3: 5 . 4 . 3 = 60
length of 4: 5 . 4 . 3 . 2 = 120
total of 20 + 60 + 120 = 200 possibilities.

If the code and the comments disagree, then both are probably wrong. -- Norm Schryer