Take b = 2.

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

71 is prime.

b^((n-1)/71)-1 mod n = 2723, which is a unit, inverse 8683.

11 is prime.

b^((n-1)/11)-1 mod n = 9543, which is a unit, inverse 16569.

(11^2 * 71) divides n-1.

(11^2 * 71)^2 > n.

n is prime by Pocklington's theorem.