Well, depends who you ask. For some agender is at least a gender identity if not a gender in and of itself. For some it means no gender at all, for some it means a gender that embodies the nothing between male and female,... there just isn't one clear definition. In my opinion agender is not a gender so pangender wouldn't include agender necessarily. But every pangender person can decide for themselves if they are also agender as part of their identity or not.