Wallis product

In mathematics, Wallis' product for π, written down in 1655 by John Wallis, states that

Related Topics:
Mathematics - π - 1655 - John Wallis

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prod_{n=1}^{infty} rac{(2n)(2n)}{(2n-1)(2n+1)} = rac{2}{1} cdot rac{2}{3} cdot rac{4}{3} cdot rac{4}{5} cdot rac{6}{5} cdot rac{6}{7} cdot rac{8}{7} cdot rac{8}{9} cdots = rac{pi}{2}

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