341 (number)
In number theory, 341 is a composite number and a pseudoprime to base 2. This means it satisfies Fermat's Little Theorem for the base 2, even though it is not a prime number. Fermat's Little Theorem states that if p is a prime number, then for any integer a, the number ap - a is an integer multiple of p. This can be expressed as ap ≡ a (mod p). A pseudoprime is a composite number that satisfies this congruence for a given base.
Specifically, 2341 ≡ 2 (mod 341). This makes 341 the smallest pseudoprime to base 2.
341 is the sum of the first 11 terms of the sequence 3n2 - 3n + 1 (1, 7, 19, 37, 61, 91, 127, 169, 217, 271, 331), also known as the centered hexagonal numbers.
The prime factorization of 341 is 11 x 31. This fact immediately confirms that 341 is not prime.