Primality proof for n = 1399:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=233.html>233 is prime.</a>
<br>b^((n-1)/233)-1 mod n = 63, which is a unit, inverse 644.
<p>(233) divides n-1.
<p>(233)^2 > n.
<p>n is prime by Pocklington's theorem.