Primality proof for n = 1601:
<p>Take b = 3.
<p>b^(n-1) mod n = 1.
<p><a href=5.html>5 is prime.</a>
<br>b^((n-1)/5)-1 mod n = 441, which is a unit, inverse 167.
<p><a href=2.html>2 is prime.</a>
<br>b^((n-1)/2)-1 mod n = 1599, which is a unit, inverse 800.
<p>(2^6 * 5^2) divides n-1.
<p>(2^6 * 5^2)^2 > n.
<p>n is prime by Pocklington's theorem.