Take b = 2.

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

29 is prime.

b^((n-1)/29)-1 mod n = 900, which is a unit, inverse 3784.

11 is prime.

b^((n-1)/11)-1 mod n = 4051, which is a unit, inverse 4219.

(11 * 29) divides n-1.

(11 * 29)^2 > n.

n is prime by Pocklington's theorem.