Answer:
a {1, 2, 3, 5, 7, 11, 13, 17.}
Step-by-step explanation:
Number one is not a prime number.
Indeed, the definition of a prime number is to be divisible by two distinct integers, 1 and itself. Concerning the number 1, the two divisors 1 and itself are not distinct: they are equal. Therefore, 1 does not match the definition of a prime number, and therefore is not a prime number!
