[Tex/LaTex] Binomial coefficient with brackets

symbols

Is there any way to write a binomial coefficient that has brackets in place of parenthesis?

Another way to write what I want would be to get a fraction without the horizontal bar between the denominator and the numerator, and then surround it with big brackets, but is this possible?

Best Answer

You can tap into amsmath's \genfrac:

enter image description here

\documentclass{article}

\usepackage{amsmath}
\newcommand{\stirlingii}{\genfrac{\{}{\}}{0pt}{}}

\begin{document}

There is $\binom{a}{b}$ and $\stirlingii{a}{b}$ and also
\[
  \binom{a}{b} \text{ and } \stirlingii{a}{b}.
\]

\end{document}

\genfrac{<ldelim>}{<rdelim>}{<width>}{<style>}{<numerator>}{<denominator>} sets a fraction braced by <ldelim> and <rdelim> in a fraction-like style with horizontal rule of width <width>. The optional <style> can force the output to be in any of the four math styles.

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