Timeline for The cotangent sum $\sum_{k=0}^{n-1}(-1)^k\cot\Big(\frac{\pi}{4n}(2k+1)\Big)=n$
Current License: CC BY-SA 4.0
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| Aug 10, 2020 at 16:01 | vote | accept | bryanjaeho | ||
| Aug 10, 2020 at 14:01 | comment | added | user44143 | I googled "alternating sum odd cotangent", and found this, by Bruce Berndt and Boon Pin Yeap, which has a good set of references for identities like this: sciencedirect.com/science/article/pii/S0196885802000209 | |
| Aug 10, 2020 at 13:59 | answer | added | Iosif Pinelis | timeline score: 4 | |
| Aug 10, 2020 at 13:52 | history | edited | GH from MO |
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| Aug 10, 2020 at 13:49 | comment | added | GH from MO | These kind of identities are well-known (folklore). For example, one of the homework problems in my introductory complex analysis course is the following. Let $n=2m+1$ be an odd positive integer. Then $\sum_{k=-m}^m\tan(z+k\pi/n)=n\tan(nz)$. (Specialize this to $z=\pi/(4n)$.) | |
| Aug 10, 2020 at 13:38 | history | edited | bryanjaeho |
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| Aug 10, 2020 at 13:31 | history | asked | bryanjaeho | CC BY-SA 4.0 |