Japanese verbs are quite complex compared to English verbs (Most English verbs have five or six forms and *to be* has eight not including archaic forms). Their agglutinative nature means they have various parts which can be present or not, or can take different morphemes.

What I'm wondering is if it is possible to calculate the number of possible forms this can lead to for a typical Japanese verb.

If it's not straightforward or generally talked about, a reference to a discussion or research paper would also be a great answer.