title: What is "n nought" in terms of "big O"?
body: <p>I am wondering what the term "n not",  written n (subscript) 0, is. It is useful when proving big 0. I believe "n not" is usually determined after c.</p>
  
  <p>I am currently trying to prove 2^n = O(N!). What would c and "n not" be in this case? Why?</p>
  
  <p>Edit: I'd like to mention that I know what big O is on a high level. I understand what 2^n = O(N!) means and know why it's true. I'm just not very good at writing proofs about asymptotic notation.</p>