【答案】：4 / (x - 1))

public class TEST {public static void main(String[] args) {double x = 111;for (int n = 10000; n >= 0; n--) {int   i = 2 * n + 1;  //把i变为奇数x = 2 + (i * i / x);}// x=2+1/x'System.out.println(String.format("%.4f", 4 / (x - 1)));}
}