Take b = 2.

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

1579 is prime.

b^((n-1)/1579)-1 mod n = 537443, which is a unit, inverse 1897992.

13 is prime.

b^((n-1)/13)-1 mod n = 817126, which is a unit, inverse 1608490.

(13 * 1579) divides n-1.

(13 * 1579)^2 > n.

n is prime by Pocklington's theorem.