Primality proof for n = 983809:
<p>Take b = 7.
<p>b^(n-1) mod n = 1.
<p><a href=61.html>61 is prime.</a>
<br>b^((n-1)/61)-1 mod n = 219357, which is a unit, inverse 601026.
<p><a href=7.html>7 is prime.</a>
<br>b^((n-1)/7)-1 mod n = 963889, which is a unit, inverse 689901.
<p><a href=3.html>3 is prime.</a>
<br>b^((n-1)/3)-1 mod n = 143450, which is a unit, inverse 608055.
<p>(3^2 * 7 * 61) divides n-1.
<p>(3^2 * 7 * 61)^2 > n.
<p>n is prime by Pocklington's theorem.