Exemples d’utilisation ici: http://irem.univ-reunion.fr/spip.php?article970
divisors(n) yields the list of the divisors of an integer n;
cd(a,b) (“common divisors”) yields the lists of the common divisors of a and b;
gcd(a,b) yields the greatest of the common divisors
and isPrime(n) is a test for the primality of the integer n.