Primality proof for n = 53:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=13.html>13 is prime.</a>
<br>b^((n-1)/13)-1 mod n = 15, which is a unit, inverse 46.
<p>(13) divides n-1.
<p>(13)^2 > n.
<p>n is prime by Pocklington's theorem.