is_prime(997)
factor(156090980)
factor(2^101-1)
prime_pi(7919)
next_prime(7919)
prime_range(10000,10100)
for n in range(1000,1100):
    if(is_prime(n) and n%4==1):
        print(n)  
for n in range(1,1200):
    if(is_prime(n) and is_square(n-1)):
        print(n)
n=10000;
for i in range(n/2+1):
    if is_prime(i) and is_prime(n-i): print(i,n-i)
for i in range(100000000,100001000):
    if is_prime(i) and is_prime(i+2): print(i,i+2)