Primality proof for n = 1213:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=101.html>101 is prime.</a>
<br>b^((n-1)/101)-1 mod n = 456, which is a unit, inverse 540.
<p>(101) divides n-1.
<p>(101)^2 > n.
<p>n is prime by Pocklington's theorem.