I haven't posted in a long while as I've been busy with several proofing projects. Now I'm back, and here's a simple one to get back in the swing of things.
Then is an adverb related to time: First I catch up on my blogging friends, then I clean my house. After you finish that, then you can play.
Than is a conjunction, and is used in comparisons: I like reading blogs more than I like cleaning. As in this example, than often follows a comparison word such as better than, more than, other than.
I don't believe I've ever seen than used when then is appropriate, but let's not substitute then when the correct word is than.