# Multiple horizontal alignment points in equation

This seems like it would be easy, but I don't see an environment that accounts for this. I'd like to horizontally align corresponding elements in a multi-line equation.

Σk^2 = 1 + 2 + 3 + ... + n
+ 2 + 3 + ... + n
+ 3 + ... + n
...
+ n

• Welcome to TeX SX! What should be aligned, exactly? – Bernard Mar 22 '18 at 0:27
• Hi, I'd like it to result graphically like the code snippet above. I've used the align* environment frequently, but that would only allow the first alignment point. I want all of the 2's, 3's, ...'s, n's aligned correspondingly. – Alexander Vornsand Mar 22 '18 at 0:29

Your typesetting objective is much easier to achieve with an array environment than it is with an align* environment.

\documentclass{article}
\usepackage{array} % for "\newcolumtype" macro
\newcolumntype{C}{>{{}}c<{{}}} % for binary and relational operators
\newcolumntype{R}{>{\displaystyle}r} & automatic display-style math mode

\begin{document}
$\setlength\arraycolsep{0pt} \renewcommand\arraystretch{1.33} \begin{array}{R*{5}{CR}} \sum k^2 & = & 1 & + & 2 & + & 3 & + & \cdots & + & n \\ & & & + & 2 & + & 3 & + & \cdots & + & n \\ & & & & & + & 3 & + & \cdots & + & n \\ & & & & & & & + & \cdots & + & n \\ & & & & & & & & \cdots & & \\ & & & & & & & & & + & n \end{array}$
\end{document}


A solution with alignat. I replaced the last \cdots with a vdots aligned with the last + signs:

\documentclass{article}
\usepackage{mathtools} %

\begin{document}
\begin{alignat*}{5}
\sum k^2 = 1 +{} & 2 &{}+{}& 3 & + & \cdots & + & n \\
{}+{}& 2 &{}+{} & 3 &{}+{}& \cdots &{}+{} & n \\
& & {}+{}& 3 & {}+{} & \cdots & {}+{} & n \\
& & & & {}+{}& \cdots & {}+{} & n \-1.5ex] & & & & & & \vdotswithin{ + }& \\[-1ex] & & & & & & {}+{}& n \end{alignat*} \end{document}  • This is also an easy, and elegant solution. Thanks! – Alexander Vornsand Mar 23 '18 at 1:34 We can exploit the symmetry and the fact that the first column in aligned is right aligned. \documentclass{article} \usepackage{amsmath,mathtools} \begin{document} \[ \begin{aligned} \sum k^2 = 1 + 2 + 3 + \cdots + n \\ {} + 2 + 3 + \cdots + n \\ {} + 3 + \cdots + n \\ {} + \cdots + n \\ \vdotswithin{+}\hphantom{n} \\ {} + n \end{aligned}
\end{document}