Primality proof for n = 673:
<p>Take b = 5.
<p>b^(n-1) mod n = 1.
<p><a href=7.html>7 is prime.</a>
<br>b^((n-1)/7)-1 mod n = 619, which is a unit, inverse 162.
<p><a href=3.html>3 is prime.</a>
<br>b^((n-1)/3)-1 mod n = 254, which is a unit, inverse 363.
<p><a href=2.html>2 is prime.</a>
<br>b^((n-1)/2)-1 mod n = 671, which is a unit, inverse 336.
<p>(2^5 * 3 * 7) divides n-1.
<p>(2^5 * 3 * 7)^2 > n.
<p>n is prime by Pocklington's theorem.