Wieferich primes

func is_wieferich_prime(p, base=2) {
    powmod(base, p-1, p**2) == 1
}

say ("Wieferich primes less than 5000: ", 5000.primes.grep(is_wieferich_prime))

Output:

Wieferich primes less than 5000: [1093, 3511]