# Java Program to Find the Sum of the Series 1/1+1/4+1/9+…1/N^2

This is the Java Program to Find the Sum of the Series 1/1+1/4+1/9+…1/N2.

Problem Description

Given a number n, write a java program to find the sum of the series 1/1+1/4+1/9+…1/N2.

Problem Solution

Start a loop from 1 to n, and add the square of the reciprocal of the loop variable to the sum.

Program/Source Code

Here is the source code of the Java Program to Find the Sum of the Series 1/1+1/4+1/9+…1/N2. The program is successfully compiled and tested using IDE IntelliJ Idea in Windows 7. The program output is also shown below.

1. ` `
2. `//Java Program to Find the Sum of the Series 1/1+1/4+1/9+...1/N^2`
3. ` `
4. `import java.io.BufferedReader;`
5. `import java.io.InputStreamReader;`
6. ` `
7. `public class Series81 {`
8. `    // Function to find the sum of the series`
9. `    public static void main(String[] args) {`
10. `        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));`
11. `        int n;`
12. `        try{`
13. `            System.out.println("Enter the number of terms in the series");`
14. `            n = Integer.parseInt(br.readLine());`
15. `        }catch (Exception e){`
16. `            System.out.println("An error occurred");`
17. `            return;`
18. `        }`
19. `        double sum = 0;`
20. `        double i;`
21. `        for(i=1; i<=n;i++){`
22. `            sum +=(1/(Math.pow(i,2)));`
23. `        }`
24. `        System.out.println("The sum is " + sum);`
25. `    }`
26. `}`
Program Explanation

In the function main(), firstly the variable n is entered, then the loop for(i=1; i<=n;i++), is used to sum the squares of the reciprocal of the loop variable.

Time Complexity: O(n).

Runtime Test Cases
```
Case 1 (Simple Test Case):

Enter the number of terms in the series
34
The sum is 1.6159505883765848```

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