Take b = 2.

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

29 is prime.

b^((n-1)/29)-1 mod n = 5938, which is a unit, inverse 4174.

13 is prime.

b^((n-1)/13)-1 mod n = 3978, which is a unit, inverse 8337.

(13 * 29) divides n-1.

(13 * 29)^2 > n.

n is prime by Pocklington's theorem.