Primality proof for n = 317:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=79.html>79 is prime.</a>
<br>b^((n-1)/79)-1 mod n = 15, which is a unit, inverse 148.
<p>(79) divides n-1.
<p>(79)^2 > n.
<p>n is prime by Pocklington's theorem.