Quote:
Originally Posted by devarajkandadai
... and b) 80*m^2 + 53*m + 7 is exactly divisible by 20.

This simply means that m=20*q+1. And therefore what you are trying to say looks like a Chernicklike recipe for 3prime factor Carmichael numbers: "if 40*q + 3, 200*q + 11 and 320*q + 17 are all prime, then their product is a Carmichael number".
With a difference that Chernick proved his and you are "just saying". To what limit did you even test it?