What is the recurrence form of Bubble-Sort I understand how bubble sort works and why it is O(n^2) conceptually but I would like to do a proof of this for a paper using the master theorem. 

As an example: The recurrence form for merge sort is T(n) = 2T(n/2) + O(n) which, using the master theorem, gives us O(n log(n)). 

I am unsure of how to do this process with Bubble sort. What equation allows us to see that it is O(n^2)?
Bubble sort uses the so-called "decrease-by-one" technique, a kind of divide-and-conquer.
Its recurrence can be written as

$$T(n) = T(n-1) + (n-1).$$