Euler solves the Basel problem by applying the Newtonian formulae for converting an infinite summation series into an infinite product series, and vice versa. The Newtonian formulae are explained on pages 358-359 of D.T.Whiteside's Mathematical Papers of Isaac Newton vol 5. This comment submitted by Peter L. Griffiths.

CAPTCHA
This question is for testing whether you are a human visitor and to prevent automated spam submissions.