6.4

include

#include <stdio.h>  int main()  {    int i,j,sun=0,n;    printf("请输入一个数 n: ");    scanf("%d",&n);        for(i=1;i<=n;i++)        { j=i*i;        sun=j+sun;        printf("j=%d\n",j);            }   printf("sun=%d\n",sun);   return 0;   }