Take b = 2.

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

71 is prime.

b^((n-1)/71)-1 mod n = 157881, which is a unit, inverse 99096.

59 is prime.

b^((n-1)/59)-1 mod n = 9686, which is a unit, inverse 162116.

(59 * 71) divides n-1.

(59 * 71)^2 > n.

n is prime by Pocklington's theorem.