long long suma=0, i, j, n, p;
cin >> n;
i=1;
while (i<=n)
{
j=1; p=1;
while (j<=i)
{ p=p*j; ++j; }
++i; suma += p;
}
cout << suma;
......... Metoda II
se poate si mai simplu:
suma=0; i=1; termen=1;
while (i<=n)
{
termen=termen*i;
suma=suma+termen;
++i;
}
cout << suma;