to display the mapping on a webpage no matter what the server encoding is, this can be used

  echo "<pre>\n";
  echo htmlentities(print_r((get_html_translation_table(HTML_SPECIALCHARS)), true));
  echo htmlentities(print_r((get_html_translation_table(HTML_ENTITIES)), true));

since get_html_translation_table() actually gives the special chars in iso-8859-1 (Latin-1) encoding, so to see the tables correctly using

  print_r(get_html_translation_table(HTML_ENTITIES));

your server needs to give a HTTP header as iso-8859-1, unless you use header() or manually set the browser's encoding setting to iso-8859-1.  And you need to view the source of the page to see the mapping.  (except English version of IE 7 outputs the page source as iso-8859-1 anyway).