const int led_pinList[7] = {13,12,14,27,26,25,33};
int num = sizeof(led_pinList)/sizeof(led_pinList[0]);
void setup() {
  for(int i = 0 ;i<num;i++){
    pinMode(led_pinList[i], OUTPUT);
  }
}

void loop() {
  for(int i = 0;i<num;i++){
    digitalWrite(led_pinList[i], LOW);
    delay(100);
    digitalWrite(led_pinList[i], HIGH);
  }

}