Can you give us the numbers please?
Provide any sort of link?
Proof or it isnt true, Im afraid.
The honest answer is that it's insanely difficult to just 'crunch the numbers.' The simplest perk configuration (read, simplest as in providing the least choices), would be 18 skill perk trees that each start a ternary perk-tree of height 2. [EDIT: This actually cuts the number of total perks from 280 to 234]. And in trying to calculate the exact number of final configurations one might get after selecting 50 perks into a playthrough, one has to then proceed in factoring in all the dependencies that each higher-tier perk has, and all their dependencies, and all theirs until you get to the root node.
It forms a relation that is dependent upon the previous user-generated numbers in the relation, something akin to the Fibonacci sequence but way more convoluted.
In other words, it's an exponential problem, (note, exponential problems depending on their size can take computers years, centuries, or even the current lifespan of the universe to compute) and that alone should be indicitave of the sheer potential size of the perk configurations. Compare a problem on an exponential scale to a problem that has constant and linear inputs (such as birthsigns, beginning attribute choices, etc), and generally, the exponential combinations blow the linear combinations out of the water.
I'm trying to write an algorithm in java right now to crunch out the total end-configurations, even though I fully expect figuring 50 perks out of 18 2-high ternary trees to be an unrealistic problem to solve.