text: #include "stdio.h"
  #include "math.h"
  
  void main() {
      int n;
      double x;
      x = 0;
      printf("x30=%2.8e\n", x);
      for (n = 30; n > 0; n--) {
          x = 1.0 / 10.0 / n - x / 10.0;
          printf("x%2d=%e\n", n - 1, x);
      }
  } 
  