Primality proof for n = 977:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=61.html>61 is prime.</a>
<br>b^((n-1)/61)-1 mod n = 76, which is a unit, inverse 90.
<p>(61) divides n-1.
<p>(61)^2 > n.
<p>n is prime by Pocklington's theorem.