Primality proof for n = 983:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=491.html>491 is prime.</a>
<br>b^((n-1)/491)-1 mod n = 3, which is a unit, inverse 328.
<p>(491) divides n-1.
<p>(491)^2 > n.
<p>n is prime by Pocklington's theorem.