Primality proof for n = 42641:
<p>Take b = 3.
<p>b^(n-1) mod n = 1.
<p><a href=41.html>41 is prime.</a>
<br>b^((n-1)/41)-1 mod n = 1217, which is a unit, inverse 10196.
<p><a href=13.html>13 is prime.</a>
<br>b^((n-1)/13)-1 mod n = 6210, which is a unit, inverse 19906.
<p>(13 * 41) divides n-1.
<p>(13 * 41)^2 > n.
<p>n is prime by Pocklington's theorem.