Primality proof for n = 188353237:

Take b = 2.

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

1613 is prime.
b^((n-1)/1613)-1 mod n = 37935592, which is a unit, inverse 82301414.

263 is prime.
b^((n-1)/263)-1 mod n = 173728644, which is a unit, inverse 125789862.

(263 * 1613) divides n-1.

(263 * 1613)^2 > n.

n is prime by Pocklington's theorem.