Primality proof for n = 18539:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=31.html>31 is prime.</a>
<br>b^((n-1)/31)-1 mod n = 17224, which is a unit, inverse 14084.
<p><a href=13.html>13 is prime.</a>
<br>b^((n-1)/13)-1 mod n = 14080, which is a unit, inverse 923.
<p>(13 * 31) divides n-1.
<p>(13 * 31)^2 > n.
<p>n is prime by Pocklington's theorem.