View Single Post
Old 2020-09-20, 20:17   #2
R. Gerbicz
R. Gerbicz's Avatar
"Robert Gerbicz"
Oct 2005

27268 Posts

Originally Posted by fivemack View Post
To find Machin-like formulae for pi, I want to find sets of N where N^2+1 has only small prime factors. Tangentially, it would be nice to have a proof that, for example, n=485298 is the largest number where n^2+1 has no prime factor greater than 53.
See: (somewhere there could be a longer computed list also).
This problem is solvable by using a Pell type equation, where on the right side there is a -1 not 1.
R. Gerbicz is offline   Reply With Quote