Primality proof for n = 307:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=17.html>17 is prime.</a>
<br>b^((n-1)/17)-1 mod n = 272, which is a unit, inverse 114.
<p><a href=2.html>2 is prime.</a>
<br>b^((n-1)/2)-1 mod n = 305, which is a unit, inverse 153.
<p>(2 * 17) divides n-1.
<p>(2 * 17)^2 > n.
<p>n is prime by Pocklington's theorem.