Primorial numbers | Rosetta Code | #11

URL to the problem page: http://rosettacode.org/wiki/Primorial_numbers


Primorial numbers are those formed by multiplying successive prime numbers.
The primorial number series is:

• primorial(0) = 1 (by definition) 
• primorial(1) = 2 (2) 
• primorial(2) = 6 (2×3) 
• primorial(3) = 30 (2×3×5) 
• primorial(4) = 210 (2×3×5×7) 
• primorial(5) = 2310 (2×3×5×7×11)
• primorial(6) = 30030 (2×3×5×7×11×13) ∙ ∙ ∙ 

To express this mathematically, primorialn is the product of the first n (successive) primes.
In some sense, generating primorial numbers is similar to factorials.
As with factorials, primorial numbers get large quickly.

Show the first ten primorial numbers (0 ──► 9, inclusive).

#include <iostream>

using namespace std;

int main() {

    int primorial[100], cnt = 1, cnt2;

    primorial[0] = 1;

    cout << "First ten primorial numbers (0 ---> 9, inclusive) are:" << endl << primorial[0] << endl;

    for (int i = 2; cnt < 10; i++) {

        cnt2 = 0;

        for (int j = 2; j <= sqrt(i); j++) {

            if (i % j == 0) {

                cnt2++;

                break;

            }

        }

        if (cnt2 == 0) {

            primorial[cnt] = primorial[cnt - 1] * i;

            cout << primorial[cnt] << endl;

            cnt++;

        }

    }

    return 0;

}

CLICK TO SEE THE OUTPUT.