Let's consider a series defined by .
then construct a series : , n from 0 to
Now discuss the convergence of the above series.
I haven't been able to think of any way of attacking this problem. It's clear that as , but it approaches 0 so desperately slowly that I very much doubt whether converges. Maybe the series of p'th powers will converge if p is large enough, but I don't see why even that should hold.
It's a very interesting problem! I hope someone can find a way to tackle it.
I can see now how to do this for p=1.
Since x_0 > 0 there is an integer k such that . The strategy is to prove by induction that . It will then follow (by comparison with the harmonic series) that diverges.
The proof relies on the fact that (for 0<x<1). This is because the power series for sin(x) is an alternating series with decreasing terms, so the partial sums are alternately greater than, and less than, the whole sum.
So suppose that . Then To complete the inductive step, we want to show that this is greater than But that is equivalent to , which is certainly true.
A slightly more elaborate form of this same argument shows that the series diverges whenever p<2. I still have no idea what happens when .