int fadeArr[] = {255, 220, 190, 160, 120, 90, 60, 30, 20, 10, 0, 0, 0};
int ledArr[]  = {2,3,4,5,6,7,8,9,10,11,12,13}; 

void setup() {
}

void loop() {

  for(int i = 0; i < 13; i++) {

      if(i < 13) {

       analogWrite(ledArr[i], 255);

       for(int k = 0; k < i; k++) {
         analogWrite(ledArr[k], fadeArr[i-k]);
          }

          }
       else {
       for(int j = 0; j < 13; j++) {
      analogWrite(ledArr[j], fadeArr[i-j]);
    }
    }


    delay(30);

      for(int i = 0; i < 13; i++) {
    analogWrite(ledArr[i], LOW);
  }

      }

    delay(300);
  
 }