#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

long int sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
   long int sum=0;
    long arr[k];
    if(k==1)
    {
        return sum=k;
    }
    else{
         long int temp=k-1;
         long int temp1=k;
         long int product=temp*temp1;
          product = product+1;
          sum=product;
          arr[0] = sum;
        //printf("%d\n",sum);
        for(int i=1;i<k;i++){
            sum  = sum+2;
            arr[i]=sum;
        }
        sum=0;
             for(int i=0;i<k;i++)
                 sum +=arr[i];
        return sum;
    }
    return 0;
}

int main() {
    int k; 
    scanf("%i", &k);
    long int answer = sumOfGroup(k);
    printf("%ld\n", answer);
    return 0;
}