Program to find the sum of the series 1^3 -2^3 + 3^3 - 4^3 + ... N^3 in C

#include <stdio.h>
#include <math.h>

int main()
{
	int n; //total number of terms
	int i; //loop counter
	long int sum; //sum of the series
	
	//read total number of terms
	printf("Enter total number of terms: ");
	scanf("%d",&n);
	
	//assign 0 to the sum
	sum = 0;
	
	for(i=1; i<=n; i++){
		//ODD terms are adding and
		//EVEN terms are subtrating
		if(i%2!=0)
			sum = sum + pow(i,3);
		else
			sum = sum - pow(i,3);
	}
	
	//print sum of the series
	printf("Sum of the series: %ld\n",sum);
	
	return 0;	
}

Output

Enter total number of terms: 5 
Sum of the series: 81

Explanation:

    Series is: 1^3 -2^3 + 3^3 - 4^3 + ... N^3
    Here, N = 5
    Then the series will be:
    = 1^3 -2^3 + 3^3 - 4^3 + 5^3
    = 1 - 8 + 27 -64 + 125
    = 81