Primality proof for n = 50993:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=3187.html>3187 is prime.</a>
<br>b^((n-1)/3187)-1 mod n = 14542, which is a unit, inverse 31605.
<p>(3187) divides n-1.
<p>(3187)^2 > n.
<p>n is prime by Pocklington's theorem.