Confusing Device Limits


i am confused about the device Limits. Maybe my understanding is wrong.

FAQ says CC2531 firmware supports 20 devices connected directly to the coordinator, and the router has a limit of 21 devices.

So, in my calculation, if i have 1 coordinator and 2 routers, the devicelimit should be 60 (20-2+21+21). In the example in the same FAQ they are writing for the Coordinator a limit of 13 (15-2). Why is the number 15 and not 20?


I’d also like an answer to this question. Is the limit in the CC2531 firmware for directly connected devices 15 or 20? I see different answers in different places. I need to know, because I’ve reached 15 and want to add another.