{authors} - {series:|[| }{series_index:0>4.1f||] }{title}
Not tested, but should be pretty close. Note that this is only for the filename, not the metadata embedded in the file. It is not sure that the app displays the filename. Then you'll have to create a plugboard instead.
See also:
http://manual.calibre-ebook.com/template_lang.html
http://manual.calibre-ebook.com/temp...and-plugboards