#include <stdio.h>
main()
{
    int i,j,n;
    long sum=0,temp=0;

    printf("Please input a number to n:\n");
    scanf("%d",&n);
    if(n<1)
    {
        printf("The n must no less than 1!\n");
        return;
    }

    for(i=1;i<=n;i++)
    {
        temp=0;
        for(j=1;j<=i;j++)
            temp+=j;
        sum+=temp;
    }
    printf("The sum of the sequence(%d) is %d\n",n,sum);
    getchar();
    getchar();