Bianca, problema 1

#include <iostream>

using namespace std;
int suma(int n){
  if (n < 0 )
     return 0;
  return 2 * n +  suma(n - 1);
}
int main()
{
    int n;
    cout << "n= "; cin >> n;
    cout<<"Rezultatul sumei este: " << suma(n);
    return 0;
}