Primality proof for n = 1019:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=509.html>509 is prime.</a>
<br>b^((n-1)/509)-1 mod n = 3, which is a unit, inverse 340.
<p>(509) divides n-1.
<p>(509)^2 > n.
<p>n is prime by Pocklington's theorem.