Difference between revisions of "Value of polygamma at 1"
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Theorem
The following formula holds: $$\psi^{(m)}(1)=(-1)^{m+1} m! \zeta(m+1),$$ where $\psi^{(m)}$ denotes the polygamma, $m!$ denotes the factorial$, and $\zeta$ denotes the Riemann zeta function.
Proof
Reference
- 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions: 6.4.2