UVA -580 组合数学

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#define ll long long
using namespace std;
ll f[];
ll g[];
ll qpow(ll a,ll b){
  ll ans=;
  while(b){
     if (b&==)ans=ans*a;
     a*=a;
     b/=;
  }
  return ans;
}
void init(){
  f[]=f[]=f[]=;
  g[]=;g[]=;g[]=;
  for (int i=;i<=;i++){
     ll sum=;
     for(int j=;j<=i-;j++){
        sum=sum+g[j-]*qpow(,i-j-);
     }
     f[i]=qpow(,i-)+sum;
     g[i]=qpow(,i)-f[i];
  }
}
int main(){
   init();
  int n;
  while(~scanf("%d",&n)&&n){
    printf("%lld\n",f[n]);
  }
  return ;
}