程序代码：

#include<stdio.h>
int main()
{
    int n,a,i,c,tmp;char s[100000];
    while(scanf("%d%d",&a,&n)!=EOF)
    {
        c=0;
        for(i=0;i<n;i++)
        {
            tmp=c+(n-i)*a;
            s[i]=tmp%10+'0';
            c=tmp/10;
        }
        while(c>0)
        {
            s[i++]=c%10+'0';
            c=c/10;
        }
        s[i]='\0';
        while(i>=0)
            printf("%c",s[--i]);
        printf("\n");
    }
    return 0;
}

程序代码：

# include <stdio.h>

int main (void)

{

    int a,n,i = 1;
    long int s1 = 0;
    long int sn = 0;

    printf ("请输入a和n的值,以空格分开:\n");
    scanf ("%d%d",&a,&n);
    printf ("a = %d,n = %d\n",a,n);

    while (i <= n)
    {

    s1 = s1 + a;

    sn = sn + s1;

    a = a * 10;

    ++i;
    }

    printf ("a+aa+aaa+...= %d\n",sn);

    return 0;
}