CareerCup

Factorial prime:
Its a prime number that is 1 less or 1 more than a factorial.
e.g

2 (0! + 1 or 1!+1)
       3(2! +1) ....

Also, what the OP meant was prime "factors" and not prime "factorials"

int count;

void check_factorial_prime(int var)
{
	int a=sqrt(var-1);
	int b=sqrt(var+1);
	int i;
	for(i=2;i<=a;i++)
	{
		if((var-1)%i==0)
			break;
	}
	if(i==a+1)
	{
		cout << var-1<<endl;
		count++;
	}
	for(i=2;i<=b;i++)
	{
		if((var+1)%i==0)
			break;
	}
	if(i==b+1)
	{
		cout << var+1<<endl;
		count++;
	}
}

int main()
{
	int n;
	cout << "Enter n : ";
	cin >> n;
	int i=3;
	count=2;
	int mult=2;
	if(n==1)
		cout << "2\n";
	else
	{
		cout << "2\n";
		cout << "3\n";
		while(count!=n)
		{
			mult=mult*(i++);
			check_factorial_prime(mult);
		}
	}
	return 0;
}

public static void getFactorialPrimes(int N)
    {
        BigInteger factorial= new BigInteger("1");
        BigInteger one= new BigInteger("1");
        for(int i=0, nextNum=1; i<N;)
        {
            if(factorial.subtract(one).isProbablePrime(100))
            {
                System.out.println(factorial.subtract(one).toString());
                i++;
            }
            if(factorial.add(one).isProbablePrime(100))
            {
                System.out.println(factorial.add(one).toString());
                i++;
            }
            factorial= factorial.multiply(new BigInteger(""+(++nextNum)));
        }
    }

pls make the question little more clear. what do you mean by "factorial primes"?

there is no number whose factorial is prime (other than 2)
yanna rascala. .. make the question clear!

while(i<N)
{
fact=factorial(i) ;
if(is_prime(fact-1))
printf("%d",fact-1) ;
if(is_prime(fact+1) )
printf("%d",fact-1) ;
}

A factorial prime is a prime number that is one less or one more than a factorial (all factorials above 1 are even). The first few factorial primes are:
2 (0! + 1 or 1! + 1), 3 (2! + 1), 5 (3! − 1), 7 (3! + 1), 23 (4! − 1), 719 (6! − 1), 5039 (7! − 1), 39916801 (11! + 1)

1] Generate a primes bool map using sieve to cover the maximum possible range

2] Start generating factorials checking the primes map for fact -+ 1 every time and decrements N whenever you find a true