A test for the primality of Fermat numbers , with and . Then the two following conditions are equivalent:
1. is prime and , where is the Jacobi symbol,
2. .
is usually taken as 3 as a first test.
A test for the primality of Fermat numbers , with and . Then the two following conditions are equivalent:
1. is prime and , where is the Jacobi symbol,
2. .
is usually taken as 3 as a first test.
Weisstein, Eric W. "Pépin's Test." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PepinsTest.html