int ledCount = 8;
int ledPins[] = { 6, 7, 8, 9, 10, 11, 12, 13 };
int ledDelay = 300;
void setup() {
  for (int thisLed = 0; thisLed <
    ledCount; thisLed++) {
      pinMode(ledPins[thisLed], OUTPUT);
    }
}
void loop() {
  for (int thisLed = 0; thisLed <
    ledCount-1; thisLed++) {
      digitalWrite(ledPins[thisLed], HIGH);
      delay(ledDelay);
      digitalWrite(ledPins[thisLed], LOW);
    }
  for (int thisLed = ledCount-1; thisLed
    > 0; thisLed--) {
      digitalWrite(ledPins[thisLed], HIGH);
      delay(ledDelay);
      digitalWrite(ledPins[thisLed], LOW);
    }
}