led_test.ino

int leds[] = {9, 10, 11, 12, 13};
const int NUMLEDS = 5;

void setup() {
  // put your setup code here, to run once:
  for (int i = 0; i < NUMLEDS; i++){
    pinMode(leds[i], OUTPUT);
    digitalWrite(leds[i], LOW);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  for (int i = 0; i < NUMLEDS; i++){
    digitalWrite(leds[i], HIGH);
    delay(500);
    digitalWrite(leds[i], LOW);
  }

}