Primality proof for n = 30773:
Take b = 2.
b^(n-1) mod n = 1.
157 is prime.
b^((n-1)/157)-1 mod n = 18481, which is a unit, inverse 10377.
2 is prime.
b^((n-1)/2)-1 mod n = 30771, which is a unit, inverse 15386.
(2^2 * 157) divides n-1.
(2^2 * 157)^2 > n.
n is prime by Pocklington's theorem.