Prime number sequence

What is the Prime Number?

A prime number is a special natural number. It has exactly two divisors – 1 and itself.

How to find a prime number?

• Take the root of the number to be examined
• Note which prime numbers exist so far
• Apply these prime numbers to the original number and see if they divide without a remainder.
• If no number is found until then, it is a prime number.

Output of Prime Sequence

def primeAlgorithm(n):
    counter = 0
    for i in range(1, n + 1):
        if n % i == 0:
            counter += 1

    if counter == 2:
        return n
    else:
        return 0

n = int(input("Enter upper limit of prime numbers: "))
for i in range(1, n):
    if primeAlgorithm(i) != 0:
        print(primeAlgorithm(i))

Output

Enter upper limit of prime numbers: 50
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47

Check if number is Prime Number

def isPrime(n):
    if n <= 1:
        return False
    for i in range(2, int(n + 1 / 2)):
        if n % i == 0:
            return False

    return True

n = int(input("Enter a number to check whether it is a prime number: "))
if (isPrime(n)):
    print(repr(n) + " is a prime number!" + " ")
else:
    print(repr(n) + " is not a prime number!" + " ")

Output

Enter a number to check whether it is a prime number: 43
43 is a prime number!