int i;
int LEDs[]{2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

void setup(){ 
  
Serial.begin(9600);
Serial.println("BEGIN");
Serial.println();

pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
pinMode(10, OUTPUT);
pinMode(11, OUTPUT);
pinMode(12, OUTPUT);


}

void loop(){

for (i=0; i<11; i++) {
digitalWrite(LEDs[i], HIGH);
delay(50);
}

/*
for (i=12; i>=0; i--) {
digitalWrite(LEDs[i], LOW);
delay(100);
}
*/

for (i=0; i<11; i++) {
digitalWrite(LEDs[i], LOW);
delay(50);
}

//delay(50);

}