I have this code

public static BigInteger Factorial(int n) {     BigInteger sum = n;     BigInteger result = n;     for (int i = n - 2; i > 1; i -= 2)     {         sum = (sum + i);         result *= sum;     }      if (n % 2 != 0)         result *= n / 2 +1;      return result; } 

I like this code it cuts iterations by half so if I need 100000! then it will do just 50000 iterations and done. But there is the problem if I need something like starting from 30000!and ending 100000!. Is any way to modify this code so we can calculate any range. As I can see this code uses the previous result to find a new one so I guess we can’t change this code.