这道题 难住小弟我了？

public class Test {    public static void main(String[] args) {        System.out.println(calc(20));    }    static double calc(int n) {        int[] nums = new int[n + 1];        nums[0] = 1;        nums[1] = 2;        for (int i = 2; i < n + 1; i++)            nums[i] = nums[i - 2] + nums[i - 1];        double sum = 0;        for (int i = 0; i < n; i++) {            sum += nums[i + 1] * 1.0 / nums[i];        }        return sum;    }}
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上面我搞错了，弄成前5个了，应该是前20个数，源代码是这样的：
Java code
public class smp{    public static void main(String args[])    {        double a=1.0,b=2.0;        double total=0;        double [] c=new double [20];         for(int i=0;i<20;i++)        {            c[i]=b/a;            double temp;            temp=b;            b=a+b;            a=temp;            total+=c[i];        }        System.out.println("total="+total);    }}
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Java code
public class Test003 {    private static int count=0;    private static double sum=0;    public double sumAdd(int n){        return this.sumAdd(2, 1, n);    }    public double sumAdd(double c,double bc,int n){        if(n>=count){            count++;            sum+=c/bc;            return sumAdd(c+bc,c,n);        }else{            return sum;        }            }    public static void main(String[] args){        Test003 test=new Test003();        System.out.println(test.sumAdd(20));    }}
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Java code
public class HelloUbuntu {    /**     * @param args     */    public static void main(String[] args) {        // TODO Auto-generated method stub        HelloUbuntu test = new HelloUbuntu();        System.out.println(""+test.sum(20));        //32.66026079864164    }    double fun1(int i){        if(i==1)return 2;        if(i==2)return 3;        return fun1(i-1)+fun1(i-2);        }    double fun2(int i){        if(i==1)return 1;        if(i==2)return 2;        return fun2(i-1)+fun2(i-2);        }    double sum(int n){        double sum=0.0;        for(int i=1; i<=n;i++){        sum+=fun1(i)/fun2(i);        }        return sum;        }}