Primality proof for n = 613:
<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 = 585, which is a unit, inverse 197.
<p><a href=3.html>3 is prime.</a>
<br>b^((n-1)/3)-1 mod n = 64, which is a unit, inverse 182.
<p>(3^2 * 17) divides n-1.
<p>(3^2 * 17)^2 > n.
<p>n is prime by Pocklington's theorem.