My code

… was written in C++ and can be compiled with G++, Clang++, Visual C++. You can download it, too. Or just jump to my GitHub repository.

       
#include <iostream>
       
#include <iomanip>
       
#include <cmath>
       
 
       
// compute next step

       
double f(double x)
       
{
       
  return floor(pow(2.0, 30.403243784 - x*x)) * pow(10, -9);
       
}
       
 
       
int main()
       
{
       
  // initial value
       
  double u = -1;
       
 
       
  // compute next steps
       
  double next = f(u);
       
  for (unsigned int i = 1; i < 513; i++)
       
  {
       
    u = next;
       
    next = f(u);
       
  }
       
 
       
  // sum of two neighbors
       
  double result = u + next;
       
 
       
  std::cout << std::fixed << std::setprecision(9) << result << std::endl;
       
  return 0;
       
}

This solution contains 5 empty lines, 4 comments and 3 preprocessor commands.