How do you use summation(∑) in LaTeX? | Sigma symbol
math mode - making a big summation sign - TeX - LaTeX Stack Exchange
1,080 Summation Symbol Images, Stock Photos, 3D objects, & Vectors | Shutterstock
math mode - make summation sign big without affecting the size of lower bound of summation - TeX - LaTeX Stack Exchange
math mode - making a big summation sign - TeX - LaTeX Stack Exchange
How to write Sigma(∑,σ) symbol in LaTeX?
math operators - How do I make a $\sigma$ the same size as an uppercase $\sum$ with a symbol or letter in the center of the hole of the $\sigma$? - TeX -
symbols - Big \sum instead of small \sum in array environment - TeX - LaTeX Stack Exchange