Primality proof for n = 11987:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=461.html>461 is prime.</a>
<br>b^((n-1)/461)-1 mod n = 5637, which is a unit, inverse 9482.
<p>(461) divides n-1.
<p>(461)^2 > n.
<p>n is prime by Pocklington's theorem.