Primality proof for n = 438281:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=10957.html>10957 is prime.</a>
<br>b^((n-1)/10957)-1 mod n = 27604, which is a unit, inverse 232938.
<p>(10957) divides n-1.
<p>(10957)^2 > n.
<p>n is prime by Pocklington's theorem.