#include<string> #include<cstring> #include<iostream> #include<cstdio> #include<algorithm> #include<cmath> #include<vector> #include<cstring> using namespace std; //int a[1000][1000]; int cal(int a, int b) { int temp = b; int temp1 = a; int num = 1; int num1 = 1; while (temp--) { num *= a; a--; } temp = b; while (temp--) { num1 *= b; b--; } return num / num1; } int main() { int n; while (cin >> n) { int z = 0; long long sum = 0; while (z <= n) { sum += pow(2, n - z)*cal(n, z); z += 2; } cout << sum << endl; } } |
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