where is a hypergeometric function and is a generalized hypergeometric function.
Clausen's Product Identity
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References
Koepf, W. Hypergeometric Summation: An Algorithmic Approach to Summation and Special Function Identities. Braunschweig, Germany: Vieweg, p. 118, 1998.Referenced on Wolfram|Alpha
Clausen's Product IdentityCite this as:
Weisstein, Eric W. "Clausen's Product Identity." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ClausensProductIdentity.html