Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Can someone help me prove that the following series $S$ converges:


I would appreciate any help in constructing a simple proof.

share|improve this question
I am wrong and sorry for it. –  gaoxinge Jan 26 '14 at 4:34
I believe it is hard, and there was a similar question with tangent but I can't find it.. –  user21820 Jan 26 '14 at 5:16
I think it may be an open problem, see: math.stackexchange.com/questions/20555/… –  user901823 Jan 26 '14 at 7:27
@user901823 fantastic lol –  Ethan Jan 26 '14 at 7:34

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.