int relayPin[] = {3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
int relays = sizeof(relayPin) / sizeof(relayPin[0]);

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

void loop() {
  for (int i = 0; i < relays; i++) {
    digitalWrite(relayPin[i], HIGH);
    delay(450);
    digitalWrite(relayPin[i], LOW);
    delay(50);
  }
}