Primality proof for n = 3736981:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=1597.html>1597 is prime.</a>
<br>b^((n-1)/1597)-1 mod n = 2483303, which is a unit, inverse 960463.
<p><a href=13.html>13 is prime.</a>
<br>b^((n-1)/13)-1 mod n = 409531, which is a unit, inverse 351715.
<p>(13 * 1597) divides n-1.
<p>(13 * 1597)^2 > n.
<p>n is prime by Pocklington's theorem.