Primality proof for n = 1206781:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=20113.html>20113 is prime.</a>
<br>b^((n-1)/20113)-1 mod n = 78447, which is a unit, inverse 709359.
<p>(20113) divides n-1.
<p>(20113)^2 > n.
<p>n is prime by Pocklington's theorem.