Difference between revisions of "Value of derivative of trigamma at positive integer plus 1/2"
From specialfunctionswiki
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==Theorem== | ==Theorem== | ||
The following formula holds: | The following formula holds: | ||
− | $$\psi^{ | + | $$\psi^{(1)} \left( n + \dfrac{1}{2} \right)=\dfrac{\pi^2}{2} - 4 \displaystyle\sum_{k=1}^n \dfrac{1}{(2k-1)^2},$$ |
− | where $\psi^{( | + | where $\psi^{(1)}$ denotes the [[trigamma]] and $\pi$ denotes [[pi]]. |
==Proof== | ==Proof== |
Revision as of 20:24, 11 June 2016
Theorem
The following formula holds: $$\psi^{(1)} \left( n + \dfrac{1}{2} \right)=\dfrac{\pi^2}{2} - 4 \displaystyle\sum_{k=1}^n \dfrac{1}{(2k-1)^2},$$ where $\psi^{(1)}$ denotes the trigamma and $\pi$ denotes pi.
Proof
References
- 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): 6.4.5