By Doron Zeilberger

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Written: June 26, 2011.

This quickie was written after Dan Haran sent me the following question .

Added Jan. 18, 2012: Christophe Vignat commented that a yet simpler version of the first simple proof of the fact that

(-1)

x

Taking x=-1 yields the identity.

I thank Christophe for his elegant remark, and remark in my turn that a trivial extension of my first proof (replace -1 by t) (x is already taken in the paper) yields the famous connection formula that he used.

Personal Journal of Shalosh B. Ekhad and Doron Zeilberger