Take b = 2.

b^(n-1) mod n = 1.

29 is prime.

b^((n-1)/29)-1 mod n = 15608, which is a unit, inverse 8922.

17 is prime.

b^((n-1)/17)-1 mod n = 4737, which is a unit, inverse 16834.

(17 * 29) divides n-1.

(17 * 29)^2 > n.

n is prime by Pocklington's theorem.