const byte ledPins[] = {7, 8};//declare pin numbers for two LEDs
unsigned long sequenceStartTime;

void setLeds()
{
  long time = millis() - sequenceStartTime;
  if (time < 100)
  {
    digitalWrite(ledPins[0], HIGH); //first LED ON during first 5 seconds in a sequence
    digitalWrite(ledPins[1], LOW);

  }
  else if(time < 300)
{
  digitalWrite(ledPins[0], LOW); //both LEDs OFF until half-time
    digitalWrite(ledPins[1], LOW);


  }
  else if(time < 600) // second LED ON
{
  digitalWrite(ledPins[0], LOW);
    digitalWrite(ledPins[1], HIGH);
  }
  else if(time < 900) // both LEDs off until end of sequence
{
  digitalWrite(ledPins[0], LOW);
    digitalWrite(ledPins[1], LOW);
  }
  else sequenceStartTime = millis(); // each 16 seconds we start a new sequence
}


void setup()
{
  Serial.begin(9600);
  pinMode(ledPins[0], OUTPUT);
  pinMode(ledPins[1], OUTPUT);
}

void loop()
{
  setLeds();
}