整數f(整數n)
{
int x = 0;
int I = 0;
while(n & gt;0)
x = 2 * x+1;
i++;
如果(i==2)
{ x = 4;}
n-;
}
返回x;
void main()
int n;
scanf("%d ",& ampn);
printf("%d ",f(n));