const int LED_PINS[] ={10, 11, 12, 13};

void setup() {
pinMode(LED_PINS[0], OUTPUT);
pinMode(LED_PINS[1], OUTPUT);
pinMode(LED_PINS[2], OUTPUT);
pinMode(LED_PINS[3], OUTPUT);

}

void loop() {
  digitalWrite(LED_PINS[0], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[0], LOW);

  digitalWrite(LED_PINS[1], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[1], LOW);

  digitalWrite(LED_PINS[2], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[2], LOW);

  digitalWrite(LED_PINS[3], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[3], LOW);

  digitalWrite(LED_PINS[3], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[3], LOW);

  digitalWrite(LED_PINS[2], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[2], LOW);

  digitalWrite(LED_PINS[1], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[1], LOW);

  digitalWrite(LED_PINS[0], HIGH);
  delay(1000);
  digitalWrite(LED_PINS[0], LOW);

}