[Tex/LaTex] Summation Symbol

Question

Want to write a summation symbol in the similar form in the attachment. Please advice.

Answer 1

\documentclass[]{article}

\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{calc}
\newlength{\depthofsumsign}
\setlength{\depthofsumsign}{\depthof{$\sum$}}
\newlength{\totalheightofsumsign}
\newlength{\heightanddepthofargument}

% https://tex.stackexchange.com/questions/22773/making-a-big-summation-sign
\newcommand{\nsum}[1][1.4]{
  \mathop{%
    \raisebox
    {-#1\depthofsumsign+1\depthofsumsign}
    {\scalebox
      {#1}
      {$\displaystyle\sum$}%
    }
  }
}

\begin{document}

\[
\sum_k^n \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} = \nsum[2]_k^n \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}
\]

\end{document}