On Ramanujan's curious equality for $\sqrt{2\,(1-3^{-2})(1-7^{-2})(1-11^{-2})\cdots} $
Posted by Tito Piezas III, at math.stackexchange.com,
In Ramanujan's Notebooks, Vol IV, p.20, there is the rather curious relation for primes of form $4n-1$, $$\sqrt{2\,\Big(1-\frac…