# How to find other Ramanujan-type continued fractions

In a letter to G.H Hardy on January $13^{\text{th}}$, Ramanujan posted this interesting continued fraction:$$\cfrac {1}{1+\cfrac {e^{-2\pi}}{1+\cfrac {e^{-4\pi}}{1+\cfrac {e^{-6\pi}}{1+\cfrac {e^{-8\pi}}{1+\ddots}}}}}=\left(\sqrt{\dfrac {5+\sqrt5}2}-\dfrac {1+\sqrt5}2\right)\sqrt{e^{2\pi}}\tag1$$ I find this interesting that an infinite continued fraction can be represented by a finite nested radical!

Question:

1. Is there a way to generate similar identities to $(1)$?
2. How did Ramanujan come up with $(1)$ in the first place?
• Identity (1) is immediately obvious to the most casual observer. As long as that observer is Ramanujan. – Mark Fischler Jan 18 '17 at 19:28
• – Robert Israel Jan 18 '17 at 19:35
• ... and the references there. In particular, you might look at Berndt's book "Ramanujan's Notebooks: Part III". – Robert Israel Jan 18 '17 at 19:40
• The fact that it is on January 13th or February 29th without knowing the year isn't that important, don't you think :) ? – Jean Marie Jan 18 '17 at 19:59
• @RobertIsrael Do you happen to know what page in Ramanujan's Notebook? – Frank Jan 18 '17 at 21:43