void setup() {
  for (int i = 2; i <= 7; i++){
    pinMode(i, OUTPUT);
  }

}

void loop() {
  for (int i = 2; i <= 7; i++){
    digitalWrite(i, HIGH);
    delay(200);
  }
  delay(500);
  for (int i = 7; i > 1; i--){
    digitalWrite(i, LOW);
    delay(200);
  }
  delay(500);
}