\documentclass{article}

\usepackage{bbm}

\begin{document}

$A = B$

$\mathbbm{N} = \{ 0, 1, 2, 3, \ldots \}$

$\mathbbm{Z} = \{ \, n \mid n \in \mathbbm{N} \wedge -n \in \mathbbm{N} \,\}$

$x^y$

$x + \sum_x^y$
\[x + \sum_x^y\]

\end{document}