[Tex/LaTex] Insert a blank page on every page break

afterpagepage-breaking

I have slides (slides.pdf; my own construction based on scrartcl) to teach from. Students
asked to put in blank slides (to have space to put down notes). I first tried to
write a shell script (getting the page number from slides.pdf, creating a
second document blanks.pdf (same number of pages) with just blank pages, then
merging the two with pdftk), but it's tedious and requires various tools. I am
wondering if this can be done in LaTeX. I only have some explicit \clearpage
statements, but when there are longer formulas (extending over a page), there is
an automatic page break on the slides. I could imagine LaTeX knows when these
page breaks happen, so if there is a way to tell LaTeX to put in two page breaks
instead of just one, that would nicely give empty pages. Any ideas? Ideally, the
page numbers should not advance… hope that's possible (?)

\documentclass{scrartcl}
\usepackage{amsmath}
\usepackage{bm}
\usepackage{blindtext}
\begin{document}
\blindtext[4]
{\allowdisplaybreaks
  \begin{align*}
    &\phantom{{}\Leftrightarrow{}}\ \langle X_n-\hat{X}_n,Y\rangle=0,\quad\forall\,Y\in\mathcal{H}_{n-1}\\
    &\Leftrightarrow\ \underbrace{\langle
      X_n-\hat{X}_n,\sum_{k=1}^{n-1}\alpha_kX_{n-k}\rangle}_{=\,\sum_{k=1}^{n-1}\alpha_k\langle
      X_n-\hat{X}_n,X_{n-k}\rangle}=0,\quad\forall\,\alpha_1,\dots,\alpha_{n-1}\\
    &\Leftrightarrow\underbrace{\langle X_n-\hat{X}_n,X_l\rangle}_{\substack{
      =\,E((X_n-\sum_{k=1}^{n-1}\phi_{n-1,k}X_{n-k})X_l)\\
    =\,E(X_nX_l)-\sum_{k=1}^{n-1}\phi_{n-1,k}E(X_{n-k}X_l)}}\hspace{-10mm}=0,\quad\forall\,l\in\{1,\dots,n-1\}\\
    &\Leftrightarrow\ \gamma(n-l)=\sum_{k=1}^{n-1}\gamma(n-k-l)\phi_{n-1,k}\\[-1mm]
    &\Leftrightarrow\ \gamma(h)=\sum_{k=1}^{n-1}\gamma(h-k)\phi_{n-1,k},\quad\forall\,h\in\{1,\dots,n-1\}\\[-1mm]
    &\Leftrightarrow\
      \Gamma_{n-1}\bm{\phi}_{n-1}=\bm{\gamma}_{n-1}
  \end{align*}}%
\end{document}

I also found this and then tried the solution there, but it only puts in one empty page (on the next page break after the command). I wonder if this can be adjusted (?)

Another option would be to actually use a two-sided layout (and put in empty pages if the page is an even page)… but that seems to be quite a bit intrusive.

Longer Update

A minimal example of what John suggested worked well. However, when I put it in
my real document, I obtained weird errors. I then did the obvious, namely
minimize the document to a MWE. Here it is. And, yes, it is minimal… whenever
I omit a line of the following, it will produce an error, even if I replace
words in the text by other words… very strange. The error is:

LaTeX Error: Something's wrong--perhaps a missing \item.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.58   \item A
               (model for)
? 

\documentclass[paper=128mm:96mm, parskip=half-]{scrartcl}
\linespread{1.12}
\usepackage[T1]{fontenc}
\usepackage[american]{babel}
\usepackage{microtype}
\usepackage[includefoot, left=5mm, right=5mm, bottom=3.5mm, top=4mm, footskip=4mm]{geometry}
\usepackage{titlesec}
\usepackage{enumitem}
\usepackage{biblatex}
\usepackage{filecontents}
\usepackage{afterpage}
\setlist{
  align=left,
  labelsep=*,
  leftmargin=*,
  topsep=-1.2mm,
  itemsep=-1.4mm
}
\titlespacing{\subsubsection}{0mm}{0ex plus 1ex minus .2ex}{-0.8ex plus .2ex}
\setcounter{secnumdepth}{3}
\newcommand{\insertblanks}{\strut\newpage\afterpage{\insertblanks}}
\begin{filecontents*}{bib.bib}
@ARTICLE{bib:markowitz-52,}
@ARTICLE{bib:harrison-kreps-79,}
@ARTICLE{bib:harrison-pliska-81,}
\end{filecontents*}
\begin{document}
\afterpage{\insertblanks}
\subsection{Foo}
\subsubsection{Bar}
\subsubsection*{Foobar}
\begin{itemize}
\item foo bar foo bar
  \begin{itemize}
  \item or sell (\emph{put}) an asset at an agreed-upon
price (the \emph{strike price $K$}) during a predetermined period
(\emph{American}) or date (\emph{exercise date $T$}; \emph{European});
  \item \emph{Futures} (obligation for the buyer (seller) to purchase (sell) an asset at a predetermined date and price);
  \item \emph{Swaps} (any exchange of an asset for another to change the
         maturity (e.g., of a bond) or because investment objectives have changed; include currency swaps, interest rate swaps).
  \end{itemize}
\item Babylon of 1800 BC: early evidence for options to provide financial cover against crop failure
\end{itemize}
\subsubsection*{Academic innovation in the 20th century}
\begin{itemize}
\item Before 1950: Desirability of an investment was measured in terms of
its return.
\item \textcite{bib:markowitz-52}: Desirability of an investment was decided upon a risk-return diagram
(x-axis: risk, i.e., standard deviation; y-axis: expected
return). An \emph{efficient frontier} determined the optimal return for a
\item Late 20th century: Theory
      milestone for quantifying and managing financial risk)
\item Black--Scholes--Merton formula
      for the price of a European call option (Nobel Prize 1997)
\item \textcite{bib:harrison-kreps-79}, \textcite{bib:harrison-pliska-81}:
  Fundamental theorems of asset pricing
  \begin{enumerate}
  \item A (model for)
  \end{enumerate}
\end{itemize}
\end{document}

Best Answer

Note: \newpage, \pagebreak and \clearpage do nothing to an empty page, so you need to add something invisible first. BTW, \clearpage is used primarily to clear the float queue.

\documentclass{scrartcl}
\usepackage{amsmath}
\usepackage{bm}
\usepackage{afterpage}
\usepackage{mwe}

\newcommand{\repeatafter}{%
  \thispagestyle{empty}%
  \addtocounter{page}{-1}%
  \null\newpage
  \afterpage{\repeatafter}%
}

\begin{document}
\afterpage{\repeatafter}

\lipsum[1-16]
\end{document}
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