Try:
Code:
((?P<series>.+) (?P<series_index>\d+) )?(?P<title>.+) - (?P<author>[^_]+)
Optionally searches for everything up to a number as series, and saves the number as the series index. Everything afterward is the same pattern as the default. If a number is not detected, it will fallback on the regular template. Warning -- If your title has a number in it, and there is no series, the title up to and including the number will be detected as series.