You've been brewing over this all day with no break through, yet Magik here does the work and figures it out independently and you still fail to see the obvious? And I don't think Magik has been spending hours wrestling with the concept.... heck I discovered the every other block thing that you all are up in arms about in beta through empirical observation... didn't even need the block explorer or the source code to do it.... so what really is your problem?
This answer?
6 * (1.13^69) = 27578.0688
Only one small problem....
Difficulty isn't 27,578 right now.
Other than that small glitch your right, it makes perfect sense.
In case he refutes that's the answer Magik came up with...
edit: difficulty started at 8? or you could think of it as difficulty starting at 6.03 after first retarget?
6 * (1.13^69) = 27578.0688