Take b = 2.

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

131 is prime.

b^((n-1)/131)-1 mod n = 283074, which is a unit, inverse 332528.

47 is prime.

b^((n-1)/47)-1 mod n = 340628, which is a unit, inverse 257949.

(47 * 131) divides n-1.

(47 * 131)^2 > n.

n is prime by Pocklington's theorem.