GAP Manual: 10.15. Primes

Primes[ n ]

Primes is a set, i.e., a sorted list, of the 168 primes less than 1000.

Primes is used in IsPrimeInt (see IsPrimeInt) and FactorsInt (see FactorsInt) to cast out small prime divisors quickly.

    gap> Primes[1];
    2
    gap> Primes[100];
    541