Primality proof for n = 407969:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=61.html>61 is prime.</a>
<br>b^((n-1)/61)-1 mod n = 214454, which is a unit, inverse 258042.
<p><a href=19.html>19 is prime.</a>
<br>b^((n-1)/19)-1 mod n = 310925, which is a unit, inverse 182641.
<p>(19 * 61) divides n-1.
<p>(19 * 61)^2 > n.
<p>n is prime by Pocklington's theorem.