#define KURZ 500
#define LANG 2*KURZ
#define GROSSEPAUSE 2*LANG
int i;

void setup()
{
  // initialize digital pin 13 as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
  //3x 500

  for (i=0; i<3; i++)
  {
    digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
    delay(KURZ);                        // wait
    digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
    delay(KURZ);                        // wait
  }

  for (i=0; i<3; i++)
  {
    digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
    delay(LANG);                        // wait
    digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
    delay(LANG);                        // wait
  }            // wait

  for (i=0; i<3; i++)
  {
    digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
    delay(KURZ);                        // wait
    digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
    delay(KURZ);                        // wait
  }          // Grosse Pause
delay(GROSSEPAUSE);
}