#include <stdio.h>
#include <stdlib.h>

int main()
{
    int n,s=0,i;
    printf("Problema calculeaza suma tuturor numerelor de la 1 la n, in perechi \nde produse a cate doua numere consecutive (1*2+2*3+...+(n-1)*n)\n");
    printf("Introduceti valoarea lui n: ");
    scanf("%d",&n);
    for(i=1;i<=n;i++) s=s+i*(i+1);
    printf("Suma=%d", s);
    return 0;
}