Primality proof for n = 1512421:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=277.html>277 is prime.</a>
<br>b^((n-1)/277)-1 mod n = 1384168, which is a unit, inverse 1214767.
<p><a href=13.html>13 is prime.</a>
<br>b^((n-1)/13)-1 mod n = 944448, which is a unit, inverse 1388338.
<p>(13 * 277) divides n-1.
<p>(13 * 277)^2 > n.
<p>n is prime by Pocklington's theorem.