Saturday, 1 September 2018

real analysis - For which p does the series suminftyn=2frac1(log1)p+(log2)p+cdots+(logn)p converge?

Suppose an=1(log2)p+(log3)p+...+(logn)p for n2 and p>0. For which values of p does n=2an converge?



So, when p1, an1(n1)(logn)p for n2. Let bn=1(n1)(logn)p. Then bn diverges since p1. Therefore by comparison test an diverges when p1.



When p>1, an1(logn)p. Let cn=1(logn)p. If cn converges then I will win. But now I am stuck. Is cn converges? Then how can I prove it? If not how can I conclude the state of convergence of an for p>1?



Can anybody please help?

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