int ledPins[8] = {23, 22, 21, 19, 18, 17, 16, 15};

void setup() {
  for (int i = 0; i < 8; i++)
pinMode(ledPins[i], OUTPUT); 
}

void loop(){
  for (int i = 0; i < 8; i++){
    analogWrite(ledPins[i], 255);

    delay(100);
      analogWrite(ledPins[i],  0);
  }
}