void setup() {
  // put your setup code here, to run once:
  for(int LED = 2; LED<=13 ; LED++){
    pinMode(LED, OUTPUT);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  for (int LED = 2; LED<= 13; LED++){
    digitalWrite(LED, HIGH);
    delay(200);
    digitalWrite(LED, LOW);
  }
  for(int LED=2; LED<=13; LED++){
    digitalWrite(LED, LOW); 
    delay(50);
  }
  for(int LED=13; LED>=2; LED--){
  digitalWrite(LED, HIGH); 
  delay(200);
  digitalWrite(LED, LOW);
  }
  for(int LED=2; LED<13; LED++){
  digitalWrite(LED, LOW); 
  delay(50);
  }
  }