Take b = 2.

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

17 is prime. b^((n-1)/17)-1 mod n = 315, which is a unit, inverse 795.

5 is prime. b^((n-1)/5)-1 mod n = 210, which is a unit, inverse 512.

(5 * 17) divides n-1.

(5 * 17)^2 > n.

n is prime by Pocklington's theorem.