Write a program which reads a positive integer value n, calculates and shows the result of the expression: $$\sum_{i=1}^{n}\frac{i+3}{i^2-5}$$

#include<stdio.h>
#include<conio.h>

int main()
{
	int N, i ;
	double sum;
	sum = 0;
	
	do{
	    printf("Enter an integer: ");
	    scanf("%d", &N);
	}while(N <0);
	
	// denominator could never be equal to 0

    	for(i=1; i <=N; i+=3)
        	sum+= (double)(i+3) / (i*i - 5);
        
    	printf("Sum = %lf \n", sum);
 
	return 0;
}