Euler's Constant

If we define
\[ \gamma_n = \left(\sum_{i=1}^n \frac{1}{i}\right) - \ln n \]
then Euler's constant is given by
\[ \gamma = \lim_{n \to \infty} \gamma_n \]
where \(\sum\) is the summation sign and \(\displaystyle{\lim_{n \to \infty}}\) is the limit of a sequence.