C program to evaluate the given series using recursive function sum

Write a complete program to evaluate the given series using recursive function sum( ). Here n is user dependent.

1 + 2 + 3 +…+ n

#include <stdio.h>   
int sum(int);
int main() 
{ 
	int num,ans;
	printf("Enter the Number of Term in Series : ");
	scanf("%d",&num);
	ans=sum(num);
	printf("Sum of Series : %d",ans);
    return 0; 
}
int sum(int n)
{
	if(n==1)
	{
		return 1;
	}
	else
	{
		return n+sum(n-1);
	}
}

Enter the Number of Term in Series : 5

Sum of Series : 15