Prime on the product symbol

I want to have a primed product symbol, i.e. something like

$\prod^\prime$

but it puts the prime on top of the product symbol instead of next to it (as a superscript, as it usually works). Does anyone know how to do this?

• Just curious, is it a conventional notation, or your own thing? And what does it stand for? – Jeon Oct 2 '16 at 21:08
• The notation is introduced by my teacher in a homework assignment to denote a product which only runs till a certainly value. Of course, one should just use the natural limits that come with \prod, but I guess everyone has its own way. – B. Pasternak Oct 2 '16 at 21:18

The amsmath package has a \sideset command for this purpose: \documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{equation*}
\sideset{}{'}\prod_{n=-k}^k \frac{a_n}{n}
\end{equation*}

\end{document}

The general syntax is

\sideset{_a^b}{_c^d}\sum

producing and works on any large operator \prod, \sum, etc.

You have to detach the superscript from the operator. Below I've inserted a \vphantom that is the size of \prod: \documentclass{article}

\begin{document}

$\prod_{i=0}^n f_i \quad \prod{\vphantom\prod}'$

\end{document}