I need to evaluate the product .
I've found this identity: , which looks useful but isn't quite what I need.
Does anyone know of a generalisation of this identity so that the lower range is ?
Yes, sorry I meant -1 of course.
What I think you're trying to do is this:
Let so that
If that's what you mean, then your next part is wrong, since the identity in my first post doesn't apply.
Or did I misunderstand?
Think about the particular case of the product that arises when . There is then only one term in the product, and it is equal to . For most values of n, there is no explicit formula for in terms of more elementary functions of n. So even in that special case, there is no satisfactory solution to the problem.