const byte ledPin[4] = {5, 4, 3, 2};

void setup() {
  Serial.begin(115200);
  Serial.println("\nHi Mom!\n");

  for (int ii = 0; ii < 4; ii++) {
    pinMode(ledPin[ii], OUTPUT);
    digitalWrite(ledPin[ii], LOW);
  }
}

int beatCount = 3;

void loop() {
  digitalWrite(ledPin[beatCount], LOW);

  beatCount++;
  if (beatCount == 4) beatCount = 0;

  digitalWrite(ledPin[beatCount], HIGH);

  Serial.print("and the beat is ");
  Serial.println(beatCount + 1);       // a white-ish lie!
  
  delay(777);
}