Primality proof for n = 2903:

Take b = 2.

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

1451 is prime.
b^((n-1)/1451)-1 mod n = 3, which is a unit, inverse 968.

(1451) divides n-1.

(1451)^2 > n.

n is prime by Pocklington's theorem.