Primality proof for n = 4957:

Take b = 2.

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

59 is prime.
b^((n-1)/59)-1 mod n = 2576, which is a unit, inverse 483.

7 is prime.
b^((n-1)/7)-1 mod n = 2694, which is a unit, inverse 4911.

(7 * 59) divides n-1.

(7 * 59)^2 > n.

n is prime by Pocklington's theorem.