### How do I get the output of this text in latex with sagetex?

Using Sage\TeX, one can use Sage to compute things and put them into
your \LaTeX{} document. For example, there are
~~$\sage{number_of_partitions(1269)}$ ~~`$\sage{number_of_partitions(1269)}$`

integer partitions of $1269$.
You don't need to compute the number yourself, or even cut and paste
it from somewhere.

Here's some Sage code:

\begin{sageblock}
f(x) = exp(x) * sin(2*x)
\end{sageblock}

The second derivative of $f$ is

[
\frac{\mathrm{d}^{2}}{\mathrm{d}x^{2}} \sage{f(x)} =
\sage{diff(f, x, 2)(x)}.
]

Here's a plot of $f$ from $-1$ to $1$:

\sageplot{plot(f, -1, 1)}

\end{document}