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
I give a Magik a +1 for remember the first difficulty drop and working off that 6 w/ one less transition.
Only one small problem....
Difficulty isn't 27,578 right now.
Other than that small glitch your right, it makes perfect sense.
Speaking of that difficulty drop.... WHY DID IT HAPPEN? The first 360 blocks occured w/ average time of 2.2 seconds per block vs target of 360 seconds yet difficulty went down. Got an answer for that one? Since it is so easy and nobody needs source code anyways.