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++: #include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip> 
#include <complex> 
#include <string>
#include <vector> 
#include <list>
#include <deque> 
#include <stack> 
#include <queue> 
#include <set>
#include <map>
#include <bitset>
#include <functional>
#include <utility>
#include <algorithm> 
#include <numeric> 
#include <typeinfo> 
#include <cstdio>
#include <cstdlib> 
#include <cstring>
#include <cmath>
#include <climits> 
#include <ctime>

using namespace std;
long int sum[10001];

int main(void){
	int i,n;
	sum[0]=1;
	for(i=1;i<=10000;i++){
		sum[i]=sum[i-1]+i;
	}
	while(~scanf("%d",&n)){
		printf("%d\n",sum[n]);
	}
	return 0;
}

C++: #include <cstdio>

using namespace std;

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

C++: #include<iostream>

int main(){

	int n;
	while (std::cin >> n){
		std::cout << n*n/2 + n/2 + 1 << std::endl;
	}

	return 0;
}

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

C++: main(n){for(;~scanf("%d",&n);)printf("%d\n",n*-~n/2+1);}

C++: #include<iostream>
int main(){int n;while(std::cin>>n)std::cout<<(--n*n+3*n+4)/2<<"\n";}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int main(){
	int n;
	while(scanf("%d",&n) != EOF){
		int sum = 1;
		for(int i = 1; i <= n; i++)
			sum += i;
		cout << sum << endl;
	}

	return 0;
}

C++: #include<stdio.h>
int main(void){
	
	int n;
	while(scanf("%d",&n)!=EOF){
	int a1=2;
	printf("%d\n",a1+(n-1)*(n+2)/2);
	}
	return 0;
}

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

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) for (int i = 0; i < (n); i++)

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

C++: #include <iostream>
#include <stdio.h>

using namespace std;

int main(void){
  int a_1 = 2;
  int x;
  int s = 0;

  while(scanf("%d", &x) != EOF ){
    if(x == 1){
      printf("%d\n", a_1);
    }else{
      s += a_1;
      for(int i = 2; i <= x; i++){
        s += i;
      }
      printf("%d\n", s);
    }
  }

  return 0;
}

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

C++: #include <cstdio>
int main(){int n;while(~scanf("%d",&n))printf("%d\n",(n*n+n+2)/2);}

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

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

    return 0;
}

C++: #include <cstdio>
#include <iostream>
 
int main()
{
    int n;
    while(std::cin>>n) {
        n%2 ? printf("%d\n",n*2+1):printf("%d\n",n*2);
    }
    return 0;
}

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

int main(){
	
	int ans[10010] = {};
	ans[0] = 1;
	for( int i=1 ; i<=10000 ; i++ ){
		ans[i] = ans[i-1] + i ;
	}
	
	int N;
	while( cin >> N ){
		if( cin.eof() ) break ;
		cout << ans[N] << endl ;
	}
	
	return 0 ;
}

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

int main(){
	int n;
	int area;

	while (cin >> n){
		area = 1;
		for (int i = 1; i <= n; i++){
			area += i;
		}
		cout << area << endl;
	}
	return 0;
}

C++: #include <iostream>

using namespace std;

unsigned long long int hoge(int n) {
  static unsigned long long int data[10001] = {};
  if (data[n])
    return data[n];
  return data[n] = (n == 1) ? 2 : hoge(n-1) + n;
}

int main() {
  int n;
  while (cin >> n) {
    cout << hoge(n) << endl;
  }
}

C++: #include<iostream>
#include<cstdio>
using namespace std;
 
int main(){
  int i,j,n,ans[100000],calc[100000];
 
  calc[0]=2;
  for(i=1;i<100000;i++)calc[i]=calc[i-1]+1;
  ans[1]=2;
  for(i=2;i<100000;i++)ans[i]=ans[i-1]+calc[i-2];
 
  while(cin >> n){
    cout << ans[n] << endl;
 
  }
 
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int t[10001];
int f(int x){
  if(t[x]!=0)return t[x];
  return t[x]=f(x-1)+x;
}
int main(){
  int n;
  t[0]=1;
  while(cin>>n){
    cout <<f(n)<<endl;
  }
  return 0;
}

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

int main(){
	int n;
	int sum = 2;
	int piyo = 2;
	for(int i=1; i<n; ++i){
		sum += piyo;
		piyo++;
	}
	cout << sum;
	return 0;
}

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

int main(){
  int n;

  while(cin >> n){
    int ans = 0;

    while(n > 0){
      ans += n;
      n--;
    }
    cout << ans+1 << endl;
  }

  return 0;
}

C++: #include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class t>
using table = vector<vector<t>>;
const ld eps=1e-9;

//// < "d:\d_download\visual studio 2015\projects\programing_contest_c++\debug\a.txt" > "d:\d_download\visual studio 2015\projects\programing_contest_c++\debug\b.answer"



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

	}
	return 0;
}

C++: #include <cstdio>

int line[10001];

int main(){
	int n;
	line[1] = 2;
	for(int i = 2; i < 10001; i++) {
		line[i] = line[i-1] + i;
	}
	while(scanf("%d", &n) != EOF){
		printf("%d\n", line[n]);
	}
	return 0;
}

C++: #include<stdio.h>
int main()
{
  int n,r;
  while(scanf("%d",&n)!=EOF){
    n--;
    r=(n*n+3*n)/2+2;
    printf("%d\n",r);
  }
  return 0;
}

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

using namespace std;

typedef long long ll;
int main(){
    vector<ll> vec(10001);
    vec.push_back(1);
    for(int i=1;i<=10000;i++){
        vec[i] = vec[i-1] + i;
    }
    int n;
    while(cin >> n){
        cout << vec[n] << endl;
    }
    return 0;
}

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

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