#include <iostream> using namespace std; // we're going to calculate factorial from number int main(){ cout<<"Enter n\n"; // we ask people for N int n ;cin>>n; // 1*2*... n long long num=1; //for 1!+2!+3!+...+N! long long sum = 0; // we multiply 1 * 2 * 3 ... N for (int i = 1 ; i <= n ; i++){ num *= i; sum += num; } // out the answer cout<<"the answer is: "<<sum<<endl;
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