DLMF:5.4.E2

MaRDI QIDQ2557

• Label: DLMF:5.4.E2

Digital Library of Mathematical Functions ID 5.4.E2

${\displaystyle{\displaystyle n!!=\begin{cases}2^{\frac{1}{2}n}\Gamma\left(\frac{1}{2}n+1\right),&n\text{ even},\\ \pi^{-\frac{1}{2}}2^{\frac{1}{2}n+\frac{1}{2}}\Gamma\left(\frac{1}{2}n+1\right),&n\text{ odd}.\end{cases}}}$

Symbols List

• ${\displaystyle{\displaystyle\Gamma\left(\NVar{z}\right)}}$: gamma function
• ${\displaystyle{\displaystyle\pi}}$: the ratio of the circumference of a circle to its diameter
• ${\displaystyle{\displaystyle!!}}$:
• ${\displaystyle{\displaystyle n}}$: nonnegative integer
 

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