IDNLearn.com makes it easy to find answers and share knowledge with others. Ask anything and receive prompt, well-informed answers from our community of experienced experts.

[tex] \rm \sum_{k = 0}^n \binom{n}k \frac{ ( - 1 {)}^{k} }{2k + 1} = \frac{2n!!}{(2n + 1)!!} \\ [/tex]​