Primality proof for n = 407203:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=67867.html>67867 is prime.</a>
<br>b^((n-1)/67867)-1 mod n = 63, which is a unit, inverse 323177.
<p>(67867) divides n-1.
<p>(67867)^2 > n.
<p>n is prime by Pocklington's theorem.