Finding an interval of 100 consecutive composite numbers with Python

Question

I'm trying to write a program that can determine an integer A as such as there are no prime numbers between A and A+100 ... Unfortunately, with my mediocre Python skills, this is all I managed to write:

for A in range (1,1000000):
    if is_prime(n)==False in range (A,A+3):
        print(A)

As you can see, I first tried to get it working with an interval of only 2 consecutive composite numbers. I also used a (working) function "is_prime" that determines if an integer is prime or not.

You can start yelling at me for my incompetence !

Answer 1

I recommend a sieve-style operation for performance reasons. Create a list of X numbers, mark all primes, then look for an unbroken sequence of composite numbers.

Answer 2

You're in the right ballpark. Just gotta finish the rest of the list comprehension.

for A in range (1,1000000):
    if all(is_prime(n)==False for n in range (A,A+3)):
        print(A)

style nitpick: not is_prime(n) would be preferable to is_prime(n) == False .