Primality proof for n = 42853:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=3571.html>3571 is prime.</a>
<br>b^((n-1)/3571)-1 mod n = 4095, which is a unit, inverse 25356.
<p>(3571) divides n-1.
<p>(3571)^2 > n.
<p>n is prime by Pocklington's theorem.