1CC is the chain below center numbers, 2CC is the chain above center numbers.
So you should substract 1 from the center numbers (keep doubling from origin) for 1CC.
http://en.wikipedia.org/wiki/Cunningham_chainIf I'm reading this correctly its actually the other way around.
Cunningham Chain of the first type:
![](https://ip.bitcointalk.org/?u=http%3A%2F%2Fupload.wikimedia.org%2Fmath%2Fc%2Fe%2F2%2Fce25bf0879e3ac9c8a197dc98a8be828.png&t=665&c=QXdN9Y0fuGm2Vg)
Yes, but that's not contradictory.
(n-1) * 2 + 1 = (2n - 1)
From center number you substract one.
From previous prime number you double and add one.