Primality proof for n = 256901:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=367.html>367 is prime.</a>
<br>b^((n-1)/367)-1 mod n = 112649, which is a unit, inverse 41084.
<p><a href=5.html>5 is prime.</a>
<br>b^((n-1)/5)-1 mod n = 191062, which is a unit, inverse 231191.
<p>(5^2 * 367) divides n-1.
<p>(5^2 * 367)^2 > n.
<p>n is prime by Pocklington's theorem.