Hmm, isn't there a 4x maximum increase?
If there is, after 5-6000 blocks I think it can be between 64 and 256...
0 - 2015 -> Difficulty 1
2016 - 4031 -> Difficulty 4
4032 - 6047 -> Difficulty 16
6048 - 8063 -> Difficulty 64
8064 - 10079 -> Difficulty 256
10080 - 12095 -> Difficulty 1024
12096 - 14111 -> Difficulty 4096
14112 - 16127 -> Difficulty 16384
16128 - 18143 -> Difficulty 65536
18144 - 20159 -> Difficulty 262144
Enjoy. Of course, this assumes the hash rate stays so high that the rate is going to jump by the maximum 4x every 2,016 blocks. As we get to 262,144, that may not be true.
