Take b = 2.

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

73 is prime.

b^((n-1)/73)-1 mod n = 5942, which is a unit, inverse 6633.

11 is prime.

b^((n-1)/11)-1 mod n = 12360, which is a unit, inverse 16315.

(11 * 73) divides n-1.

(11 * 73)^2 > n.

n is prime by Pocklington's theorem.