Primality proof for n = 1031:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=103.html>103 is prime.</a>
<br>b^((n-1)/103)-1 mod n = 1023, which is a unit, inverse 902.
<p>(103) divides n-1.
<p>(103)^2 > n.
<p>n is prime by Pocklington's theorem.