Exponents of 2

// This program outputs a list of exponents of 2 based on limits specified by user
#include <iostream.h>
#include <math.h>
#include <iomanip.h>
int main()
{
	unsigned long int lowExp, highExp; // initializes limits for exponent table
  unsigned long int power, answer; // initializes the variables for power and result
  cout << "This program will ask you for limits, then outputs a list of powers of 2.\n\n";
  // asks for input for low power
  cout << "Enter low exponent from 0 to 20: ";
  cin >> lowExp;
  // loop that repeats as long as lowExp is under minimum 0 or over maximum 20
  while ((lowExp < 0) || (lowExp > 20))
  {
  	cout << "Try again\n";
   cout << endl << "Enter low exponent from 0 to 20: ";
   cin >> lowExp;
  }
  // asks for input of high power
  cout << endl << "Enter high exponent from 0 to 20: ";
  cin >> highExp;
  // loop that repeats as long as highExp is under minimum 0 or maximum 20
  while((highExp < 0) || (highExp > 20) || (highExp < lowExp))
  {
  	cout << "Try again\n";
   cout << endl << "Enter high exponent from 0 to 20: ";
   cin >> highExp;
  }
  cout << endl << " " << setw(2) << "X" << "	 2^X" << endl;
  cout << " " << "==" << "	=======" << endl;
  power = lowExp;
  /* loop that begins output of powers of 2,
  	repeats until reaches specified high limit */
  while(power <= highExp)
 	{
   	answer = pow(2,power);
 		cout << " " << setw(2) << power << "	" << setw(7) << answer << endl;
   	power = power + 1;
 	}
	return 0;
}