My code

… was written in C++11 and can be compiled with G++, Clang++, Visual C++. You can download it, too. Or just jump to my GitHub repository.

       
#include <iostream>
       
#include <vector>
       
 
       
int main()
       
{
       
  unsigned int maxNumber = 500000;
       
  unsigned int consecutive = 4;
       
  std::cin >> maxNumber >> consecutive;
       
 
       
  // a group of consecutive numbers might extend beyond maxNumber
       
  // therefore adjust our search range accordingly
       
  maxNumber += consecutive - 1;
       
 
       
  // count prime factors of each number (1 is not considered a prime factor)
       
  std::vector<unsigned int> primeFactors(maxNumber + 1, 0);
       
 
       
  // modified Sieve of Eratosthenes
       
  for (unsigned int i = 2; i <= maxNumber; i++)
       
    // is i a prime ?
       
    if (primeFactors[i] == 0)
       
        // all multiples of i have i as a prime factor
       
        for (unsigned int j = i; j <= maxNumber; j += i)
       
          primeFactors[j]++;
       
 
       
  // iterate over all numbers
       
  unsigned int currentRun = 0;
       
  for (unsigned int i = 2; i <= maxNumber; i++)
       
  {
       
    // match ?
       
    if (primeFactors[i] == consecutive)
       
    {
       
      currentRun++;
       
 
       
      // enough such numbers in a row ? print the first
       
      if (currentRun >= consecutive)
       
        std::cout << (i - consecutive + 1) << std::endl;
       
    }
       
    else
       
    {
       
      // reset counter
       
      currentRun = 0;
       
    }
       
  }
       
 
       
  return 0;
       
}

This solution contains 7 empty lines, 10 comments and 2 preprocessor commands.