How can I change the increment of the page numbering?

Question

I'm trying to create a somewhat specially formatted document, with some text on the recto (right side) and a graphic on the verso (left side). This is for a brochure of sorts. See below:

---------    ---------
|       |    |       |
| text  |    |  fig  |  
|       |    |       |
|   n   |    |  n+1  |
--------     ---------

My idea is to compile two separate documents -- one will have the text, and the other the graphics, and these are easy to create. With some pdftk wizardry, I can easily mix the pages together in the order they should appear, together with some additional front and back matter.

Now, I want to have page numbers on each page, and for this, they need to be incremented by two for each document. I guess I could try to do this manually, but I was kinda hoping there could be a better way to do it.

All kinds of ideas welcome. I'm using LaTeX, but ConTeXt solutions will be interesting to see as well. If you think of another way to do the whole thing, feel free to give it a go.

Bonus points for specifying arbitrary page increment.

Answer 1

This idea popped into my mind: Using \afterpage to simply increase the page counter after every page. Note the recursive call. This allows for arbitrary, but fixed page increments. Variable page increments would need some form of \increasethispagenumber{<n>} macro in the text which sets the increment. I think you get the idea.

\documentclass{article}

\usepackage{afterpage}

\def\incpage{\addtocounter{page}{1}\afterpage{\incpage}}

\begin{document}

\afterpage{\incpage}

A
\newpage
B
\newpage
C
\newpage
D
\newpage
E
\newpage
F
\end{document}

Works fine in my simple test.

Answer 2

Beside changing the page counter you can also simply change the output and leave the counter as is:

\documentclass[a4paper,10pt]{scrartcl}
\renewcommand\thepage{\number\numexpr 2*\the\value{page}\relax}
\begin{document}


a\newpage b\newpage c\newpage d\newpage
\end{document}

Answer 3

A slightly less obvious way of doing this (and probably less robust than Martin's) is to use etoolbox to patch the macro that actually outputs the page number.

\documentclass{article}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@outputpage{\stepcounter{page}}{\stepcounter{page}\stepcounter{page}}{}{}
\makeatother
\begin{document}
\section{A}\label{sec:A}\pageref{sec:A}\newpage
\section{B}\label{sec:B}\pageref{sec:B}\newpage
\section{C}\label{sec:C}\pageref{sec:C}\newpage
\section{D}\label{sec:D}\pageref{sec:D}
\end{document}

Here, the single \stepcounter{page} is replaced by two of them.