Question

Sa se scrie un program care citeste numarul natural n si determina suma S=1*2+2*3+3*4+...+n*(n+1)

Answer 1

#include <iostream>
using namespace std;
int main()
{
    int n; cin >> n;
    int S = 0;
    for (int i=1; i<=n; i++)
        S += i*(i+1);
    cout << S;
    return 0;
}

Answer 2

si asta-i foarte usoara...

#include <iostream>
using namespace std;
int main()
{  int n,s=0,p=1;
  cout<<"nr=";cin>>n;
  while(n)
  {  p=n*(n+1);
  s=s+p;
  n--;
  }
  cout<<"suma:"<<s;
}