I haven't seen both of them used at all. "After" suggests something happening later, so "then" sounds redundant. 1) "after then"= I can't think of any sentence where "after then" is used. Try "after that...". 2) "then after"= I can't think of any sentence where this is used either. Try either "then...", "then, afterwards" or "thereafter..."

"After that" and "then, afterwards" are both correct. Do they fit what you mean? Ideally, if you could give more context then this might be easier to answer.