Primality proof for n = 1861:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=31.html>31 is prime.</a>
<br>b^((n-1)/31)-1 mod n = 1546, which is a unit, inverse 449.
<p><a href=5.html>5 is prime.</a>
<br>b^((n-1)/5)-1 mod n = 757, which is a unit, inverse 1802.
<p>(5 * 31) divides n-1.
<p>(5 * 31)^2 > n.
<p>n is prime by Pocklington's theorem.