Take b = 2.

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

29 is prime.

b^((n-1)/29)-1 mod n = 11485, which is a unit, inverse 3919.

5 is prime.

b^((n-1)/5)-1 mod n = 6623, which is a unit, inverse 5363.

(5 * 29) divides n-1.

(5 * 29)^2 > n.

n is prime by Pocklington's theorem.