Can I write a series of blog entries about the same topic?

In a word, yes... provided that each blog entry is a separate issue and can be justified to be published separately.

This means that each blog entry regarding your main topic should be a complete and individual subtopic with new information not yet presented in any other entry of the series.

That is not to say that information you've presented in earlier entries into the series should not be referenced or linked to... but subsequent blog entries must be distinguishable as deserving their own, separate posting. If the only difference between blog entries is one or two paragraphs, and the rest of the information is copied from another blog entry, we may ask you to consolidate your series into a single posting or unpublish entries into your series pending further edits or information.