title: Simple Function for S(n) Big Oh
body: <p><img src="https://i.stack.imgur.com/6bLio.png" alt="enter image description here"></p>
  
  <p>Give a simple function f(n) so that the sum S(n) is in Θ(f(n)).</p>
  
  <p>I don't know where to get started for this, I know the definition of Big Oh, and Big Theta but I'm unsure how to formulate a function from the Sum S(n).</p>