export to babel, sometimes a block environment is inserted.

[Uwe Brauer]

Hello

I have a org file that I want to export either to 

    1. Regular latex or

    2. To beamer. 


So I just use the corresponding export engines.

However the following minimal example puzzles me:

#+begin_src 

# -*- org-confirm-babel-evaluate: nil -*-
#+LATEX_HEADER_EXTRA:  \usepackage{booktabs}

* The  algorithm applied to the Lane-Emden equation
:PROPERTIES:
:BEAMER_env: frame
:BEAMER_opt: allowframebreaks
:END:

** The original Lane-Emden equation

#+begin_src latex :results latex replace :exports results :eval t
\begin{equation*}
  \begin{cases}
    y''(x)+\frac{2}{x}y'(x)+y^{n} &=0\\
    y(0) &= 1\\
    y'(0) &=0
  \end{cases}
\end{equation*}
where $n\in[0,5]$ is the polytropic index.
#+end_src

#+end_src


Because it exports to 

#+begin_src 
\begin{frame}[allowframebreaks]{The SLM algorithm applied to the Lane-Emden 
equation}
\begin{block}{The original Lane-Emden equation}
\begin{equation*}
    y''(x)+\frac{2}{x}y'(x)+y^{n} &=0\\
    y(0) &= 1\\
    y'(0) &=0
\end{equation*}
where $n\in[0,5]$ is the polytropic index.
\end{block}
\end{frame}

#+end_src

How can I avoid this annoying block environment?

Regards

Uwe Brauer