const int numLEDs = 5;
int i = 0;

int ledPins[numLEDs] = {2, 3, 4, 5, 6};

void setup() {
  // put your setup code here, to run once:
for (i = 0; i < numLEDs; i++) {
  pinMode(ledPins[i], OUTPUT);
 }
}

void loop() {

for ( i = 0; i <numLEDs; i++) {
  digitalWrite(ledPins[i], HIGH);
  delay(500);
  digitalWrite(ledPins[i], LOW);
}
}