Primality proof for n = 829:
Take b = 2.
b^(n-1) mod n = 1.
23 is prime.
b^((n-1)/23)-1 mod n = 68, which is a unit, inverse 573.
3 is prime.
b^((n-1)/3)-1 mod n = 124, which is a unit, inverse 234.
(3^2 * 23) divides n-1.
(3^2 * 23)^2 > n.
n is prime by Pocklington's theorem.