Go: package main

import (
        "fmt"
)

func main() {
        var num int
        for {
                _, err := fmt.Scan(&num)
                if err != nil {
                        break
                } else {
                        fmt.Printf("%d\n", (num*num+num+2)/2)
                }
        }
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
using namespace std;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define FOR(i, m, n) for(int i=(m); i<(n); ++i)
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
#define mp make_pair
#define pb push_back
#define Cout(x) cout << (x) << endl
#define Cout2(x, y) cout << (x) << " " << (y) << endl
#define dump(x) cout << #x << " = " << (x) << endl;
#define forauto(i, a) for(auto i : a)cout << i << " "; puts("");
typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<string> VS;
typedef vector<bool> VB;
typedef vector<vector<int>> VVI;
typedef pair<int, int> PII;
const int inf = 1e9;
const double pi = acos(-1.0);

int main() {
	VI num(10003);
	num[1] = 2;
	int x = 2;
	for (int i = 2; i <= 10000; i++) {
		num[i] = num[i - 1] + x;
		x++;
	}

	int n;
	while (cin >> n) {
		Cout(num[n]);
	}
}

C++: #include<iostream>
#include<algorithm>

using namespace std;

int main(){
    int n;
    while(cin >> n){
	cout << n * (n + 1) / 2 + 1 << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int main(){
   int n;
   int a = 1
   while(cin>>n){
      if(n <= 2*a){
         cout << 2*n << endl;
      }else if(n <= 4*a){
         cout << 2*n + a << endl;
      }else if(n <= 6*a){
         cout << 2*n + 2*a << endl;
      }else{
         cout << 2*n + 4*a << endl;

   return 0;
}

C++: #include<iostream>
using namespace std;

int main(){
  int n,sum,i;
 
  while(cin >> n){
      sum=1;
      if( 0 < n && n <= 10000){
	for( i = 0 ; i <=  n ; i++){
	  sum = sum + i;
	}
	cout <<sum << endl;
      }

  }

    return 0;
}

C++: #include<iostream>
using namespace std;
 
int main(){
    int n;
    while(cin>>n){
        cout<<n*(n+1)/2+1<<endl;
    }
    return 0;
}

C++: #include<cstdio>

int main(){
	int n;
	while(~scanf("%d", &n)){
		printf("%d\n", 1 + (1 + n) * n /2);
	}	
}

C++: #include<iostream>

using namespace std;

int main(void)
{
	while(1)
	{
		int n;
		cin>>n;
		if(n==0)break;
		cout<<1+n*(n+1)/2<<endl;
	}
}

C++: #include <iostream>

using namespace std;

int main()
{
	int n;
	
	while (cin >> n){
		int num = (n + 1) * n / 2 + 1;
		cout << num << endl;
	}
	return (0);
}

C++: #include<iostream>
using namespace std;
int main() {
	int a, x;
	while (cin >> a){
		x = 1;
		for (int i = 0; i < a; i++){
			x +=(i + 1);
		}
		cout << x << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

int main() {
  int n, count = 1;
  while(cin >> n){
  for(int i = 0; i < n; i++){
    count += i + 1;
  }
  cout << count << endl;
    count = 1;
  }
     
}

C++: #include <iostream>
using namespace std;
int main() {
	int n;
	while(cin>>n) {
		int l[10001];
		l[0] = 2;
		for (int i=1;i<n;i++) {
			l[i]=l[i-1]+i+1;
		}
		cout << l[n-1] << endl;
	}
}

C++: #include<iostream>
using namespace std;
int main() {
	int n;
	while(cin >> n){
		cout << 1 + (n + 1) * n / 2 << "\n";
	}
	return 0;
}

C++: #include <iostream>
using namespace std;

int main(){
	int n;
	while( cin >> n ){
		int sum = 1;
		for( int i = 1; i <= n; i++ ) sum += i;
		cout << sum << endl;
	}
}

C++: #include <iostream>
using namespace std;
int main() {
	int n;
	while(cin >> n) {
		cout << 0.5 * n * (n + 1) << endl;
	}
}

C++: #include <iostream>
#include <cstdio>
using namespace std;

int main(){
    int n;
    while(scanf("%d",&n) != EOF){
        cout << n*2+1 << endl;
    }
}

C++: #include <cstdio>
using namespace std;

int main() {
  int n;
  while (scanf("%d", &n)==1) {
    printf("%d\n", (n*(n+1))/2+1);
  }
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

int main(){
  int num = 0;
  int dp = 2;
  int x;
  
  while(cin >> x){
    dp = 2;
    
    for(int i = 1; i<x ; ++i){
      dp += (i + 1);
    }

    cout << dp << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <utility>
#include <algorithm>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>

typedef long long int ll;


using namespace std;

vector<ll> num(10010,0);
vector<int> flag(10010,0);

ll f(int n){
	if(!flag[n]){
		if(n<2)num[n]=1;
		else num[n]=n*f(n-1);
		flag[n]=1;
	}
	return num[n];
}

int main(){
	int a;
	while(cin>>a){
		cout<<f(a)+1<<endl;
	}
}

C++: #include<bits/stdc++.h>
using namespace std;
int main(){
  int n,a=1;
  cin >> n;
  for(int i=1; i<=n; i++){
	a+=i;
  }
  cout << a << endl;
  //ans = 1 + i = 2
  //ans = 2 + i+1 = 4
  //ans = 3 + i+2 = 7
 return 0;
}

C++: #include <iostream>
using namespace std;
main(){int a;while(cin>>a){if(!a)break;cout<<1+a*(a+1)/2<<endl;}}

C++: #include<stdio.h>
int saiki(int n){
	if(n==1)return 2;
	return n+saiki(n-1);
}
int main(void){
	int n;
	while(scanf("%d",&n)!=EOF)printf("%d\n",saiki(n));
	return 0;
}

C++: #include <iostream>
using namespace std;

int get_num(int n){
	int total = 1;
	for(int i = 0;i < n; i++){
		total += i + 1;
	}
	return total;
}

int main(){
	int n;
	while(cin >> n){
		cout << get_num(n) << endl;
	}
	return 0;
}

C++: #include <iostream>
using namespace std;

int main()
{
	int n, in;
	while (cin >> in){

		n = in * 2;

		if (in > 2) n += in - 2;

		cout << n << endl;
	}
	return (0);
}

C++: #include<stdio.h>
 
int main(){
    int a;
    while(~scanf("%d",&a)){
        int ans=1;
        for(int i=0;i<a;i++){
            ans+=i+1;
        }
        printf("%d\n",ans);
    }
}

C++: #include <iostream>
#include <string>
#include <vector>
using namespace std;

int main() {
    int n;
    while (cin >> n) {
        cout << (1 + n) * n / 2 + 1 << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <math.h>
#include <algorithm>


using namespace std;
int main(){

    int x;
    while(cin>>x){
        int count=0;
        for(int i=1; i<=x; i++){
            if(i==1){
                count=2;
            }else{
                count+=i;
            }
        }
        cout<<count<<endl;
    }

}

C++: #include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;
int res[11111];
main(){
  int N;
  res[0]=1;
  res[1]=2;
  int co=2;
  for(int i=2;i<=10000;i++){
    res[i]=res[i-1]+co;
    co++;
  }
  while(~scanf("%d",&N)) printf("%d\n",res[N]);
}

C++: #include <iostream>
using namespace std;
int main(){
	int n;
	while(cin>>n){
		int area=(n*n+n+2)/2;
		cout<<area<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
using namespace std;

int main(){
	int n;
	int hoge;
	int sum = 0;
	cin >>n;
	if(n%2==0)hoge = n/2;
	else hoge = n/2+1;
	for(int i=0; i<hoge; ++i){
		sum += i+2;
		if(i+1< hoge)
		sum += i+2;
	}
	cout << sum << endl;
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int main(){
  int n,ans=0;
  cin >> n;

  for(int i=1; i<=n; i++){
	ans += n + i;
	if(i == n) break;
  }
  
  cout << ans << endl;
  //ans = 1 + i
  //ans = 2 + i+1
  //ans = 3 + i+3
 return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;

int main() {
	int a;
	while (cin >> a) {
		cout << (a + 1)*a / 2+1 << endl;
	}
}

C++: #include<iostream>
using namespace std;

int main(){
  int a[50];
  for(int i=0;i<50;i++){
    cin >> a[i];
  }
  for(int i=0;i<50;i++){
  cout << 1/2*a[i]*(a[i]+1)+1 <<endl;
  }
  return 0;
}

C++: #include<stdio.h>
int main(){
 int n;
 while(scanf("%d",&n)!=EOF){
  printf("%d\n",(n*(n-1))/2+1);
 }
 return 0;
}

C++: #include <iostream>
using namespace std;

int main() {
  int n,ans;
  while( cin >> n ) {
    ans = 2;
    for(int i=1;i<n;i++) {
      ans += i + 1;
    }
    cout << ans << endl;
    ans = 0;
  }
}