C :

#include<stdio.h>
int sl(int n){
	if(n==1){
	return 1;}else if(n==2){
		return 2;
	}
	else{
		return sl(n-1)*2-sl(n-2)+1;
} 
}
int main()
{
	int n,i,s=0;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		s=s+sl(i);
	}
	printf("%d",s);
return 0;
}

C++ :

#include <iostream>
#include <cmath>
using namespace std;
int num(int n){
	int r;
	if(n==1){
		r=1;
	}else{
		r=num(n-1)+n-1;
	}	
	
	return r;
}
int main(){
	int n,i,s;
	s=0;
	cin>>n;
	for(i=1;i<=n;i++){
		s=s+num(i);
	}
	cout<<s<<endl;
}

Pascal :

var a:array[1..1000] of qword;
   i,x,s,n:longint;
begin
read(n);
a[1]:=1;
x:=1;
for i:=2 to n+1 do
begin
a[i]:=a[i-1]+x;
inc(x);
end;
for i:=1 to n do
s:=s+a[i];
write(s);
end.

Java :

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		System.out.println(forSum2(n));
	}
	
	public static int forSum1(int n) {
		int r = 0;
		if(n == 1) {
			r = 1;
		}
		for(int i = 2;i<=n;i++) {
			r = forSum1(i-1)+i-1;
		}
		return r;
	}
	public static int forSum2(int n) {
		int r = 0;
		for(int i = 1;i<=n;i++) {
			r += forSum1(i);
		}
		return r;
	}
	
	
}

Python :

def shu(n):
    r = 0;
    if n == 1:
       r = 1;
    else:
       r = shu(n - 1) + n - 1 
    return r;

n = int(input())
s = 0
for i in range(1, n+1):
    s += shu(i)
print(s)