Primality proof for n = 121271:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=181.html>181 is prime.</a>
<br>b^((n-1)/181)-1 mod n = 85749, which is a unit, inverse 54941.
<p><a href=5.html>5 is prime.</a>
<br>b^((n-1)/5)-1 mod n = 63674, which is a unit, inverse 101435.
<p>(5 * 181) divides n-1.
<p>(5 * 181)^2 > n.
<p>n is prime by Pocklington's theorem.