C :

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
int main()
{
  //  freopen("in","r",stdin);
 //   freopen("out","w",stdout);
    int a,n;
	long total;
	long x;
	int i = 0;
	while(scanf("%d%d",&a,&n)!=EOF)
	{
	 x=1;
     total=0;
	for(i=0; i<n; i++)
	{
		x *= a;
		total += x;
	}
	total = x*2 - total;
	printf("%d\n",total);
	}


  return 0;
}

C++ :

#include<stdio.h>
#include<math.h>
int main()
{
	int a,n,sum,j;
	while(scanf("%d%d",&a,&n)!=EOF)
	{
		sum=pow(a,n);
		for(j=n-1;j>0;j--)
		{
			sum=sum-pow(a,j);
		}
		printf("%d\n",sum);
	}
	return 0;
}