C language 3-7 daffodils (enhanced version)

Output narcissus number . Enter a positive integer （3≤ n ≤7), Output all n Number of daffodils . The number of Narcissus refers to a  n  Positive integer , Its digits n The sum of the powers is equal to itself . for example 153 The cube sum of each digit of 1^3+5^3+3^3=153.
attach ： Daffodils number is also known as Armstrong number .
The number of daffodils of the three is 4 individual ：153,370,371,407;
The number of four leaf roses in four digits is 3 individual ：1634,8208,9474;
There are five pointed stars in five digits 3 individual ：54748,92727,93084;
The six digit number is only 1 individual ：548834;
There are seven stars in the Big Dipper 4 individual ：1741725,4210818,9800817,9926315;
There are eight immortals in total 3 individual ：24678050,24678051,88593477.

example ： Input n=4, Output 1634,8208,9474

#include<stdio.h>// Daffodil number enhanced version  
#include<math.h>
int main(void)
{
	int n,i,j,x,k;
	double sum=0;
	printf("Enter n:");
	scanf("%d",&n);
	printf("%d The number of daffodils is ：",n);
	if(n<3||n>7){
		printf("Invalid!\n");
	} 
	else {
			for(i=100;i<pow(10,n);i++)// except n=5, The rest are normal , There will be more 4150,4151, Need to increase digit judgment （ Already added ） 
		{
			j=i;
			sum=0;
		    while(j>0){
		    	x=j%10;
			    sum+=pow(x,n);
			    j=j/10;
			}
			if((sum==i)&&(sum>pow(10,n-1)&&sum<pow(10,n+1)))
			{
				printf("%.lf\t",sum);
		    }
		}	
	}
	
	return 0;
}