# define L 3

void setup() 
{
  Serial.begin(115200);
}

void loop() 
{
  unsigned long a[L];
  for (byte i = 0; i < L; i++)
    {
      a[i] = millis();
      delay(500);
    }
  
  Serial.print(a[0]);
  Serial.print("\t");
  Serial.print(a[1]);
  Serial.print("\t");
  Serial.println(a[2]);

}