Take b = 2.

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

37 is prime.

b^((n-1)/37)-1 mod n = 33, which is a unit, inverse 4488.

23 is prime.

b^((n-1)/23)-1 mod n = 1868, which is a unit, inverse 298.

(23 * 37) divides n-1.

(23 * 37)^2 > n.

n is prime by Pocklington's theorem.