[pdftex] writing `#', `{', `}' into auxiliary file

[Alexander Grahn]

Hello,

I'd like to write a literal `#1' (not expanded, just as a string)
and unequilibrated `{' or `}' into an auxiliary file using the
\protected at write command.

I want LaTeX to write a macro definition with arguments into this
auxiliary file on the first run, which is used in subsequent runs.

Commenting out `#' and the `{' with `\' doesn't help, because `\' will
appear in the aux.-file too.

Sorry if this question seems to be off topic, but I want to add some
kind of (reliable) physical page counter to my package for usage with
pdflatex, as incrementing some counter on every shipout doesn't yield
the expected result.

Thank you very much in advance for your help!

Alexander