Primality proof for n = 8423:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=4211.html>4211 is prime.</a>
<br>b^((n-1)/4211)-1 mod n = 3, which is a unit, inverse 2808.
<p>(4211) divides n-1.
<p>(4211)^2 > n.
<p>n is prime by Pocklington's theorem.