void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(27, OUTPUT);
}

void loop() {
  for(int i=0;i<=20;i++){
    if(i>0 && i<=5){
      digitalWrite(27, HIGH);
      delay(1000);
      Serial.println(i);
    }
    else if(i>5 && i<=10){
      digitalWrite(27, LOW);
      delay(1000);
      Serial.println(i);
    }
    else if(i>10 && i<=15){
      digitalWrite(27, HIGH);
      delay(1000);
      Serial.println(i);
    }
    else if(i>15 && i<=20){
      digitalWrite(27, LOW);
      delay(1000);
      Serial.println(i);
    }
  }
  // put your main code here, to run repeatedly:
  delay(1000); // this speeds up the simulation
}