LaTeX is Turing complete

fib.tex

\newcount \temp \newcount \fone \newcount \ftwo \newcount \counter

\newcommand{\fibonacci}[1]{
  \counter=#1
  \fone=1
  \ftwo=1
  \temp=0
  \the\fone, \the\ftwo
  \fibloop
}

\newcommand{\fibloop}{, 
  \let\next= \fibloop
  \temp=\fone
  \fone=\ftwo
  \advance \ftwo by  \temp
  \ifnum \counter=0 \let\next=\relax \else \advance \counter by -1  \fi
  \the\ftwo
  \next
}

\documentclass[a4paper]{article}

\setlength{\parindent}{0pt}
\setlength{\oddsidemargin}{0pt}
\setlength{\topmargin}{0pt}

\begin{document}
  \fibonacci{10}
\end{document}