View Code of Problem 48

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double m, z, t;
        double sum = 0.0f;
        m = 2;
        z = 1;
        t = 0;
        for(int i = 0; i < n; i ++) {
            sum += (m / z);
            t = m;
            m = m + z;
            z = t;
        }
        String res = String.format("%.6f", sum);
        System.out.println(res);
    }
}