Take b = 2.

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

79 is prime.

b^((n-1)/79)-1 mod n = 6276, which is a unit, inverse 10807.

13 is prime.

b^((n-1)/13)-1 mod n = 32464, which is a unit, inverse 20438.

(13 * 79) divides n-1.

(13 * 79)^2 > n.

n is prime by Pocklington's theorem.