Primality proof for n = 1201:

Take b = 2.

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

5 is prime.
b^((n-1)/5)-1 mod n = 104, which is a unit, inverse 358.

3 is prime.
b^((n-1)/3)-1 mod n = 569, which is a unit, inverse 610.

(3 * 5^2) divides n-1.

(3 * 5^2)^2 > n.

n is prime by Pocklington's theorem.