Carmichael Number

Carmichael Number is an odd composite number which follows the following condition applicable in Fermat's Little Theorem.

Fermat's little theorem states that if p is prime and a is not a multiple of p, then a p - 1 ≡ 1 mod p. Stated theorem gives an achievable way to detect non-primee. For a > 1, we write F(a) for the set of positive integers n satisfying a n - 1 ≡ 1 mod n. By Fermat’s theorem, F(a) includes all primes that are not divisors of a. If n ∈ F(a), then gcd(a, n) = 1, since, clearl...