Primality proof for n = 18947:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=9473.html>9473 is prime.</a>
<br>b^((n-1)/9473)-1 mod n = 3, which is a unit, inverse 6316.
<p>(9473) divides n-1.
<p>(9473)^2 > n.
<p>n is prime by Pocklington's theorem.