void setup() {
  Serial.begin(115200);
  if(!Serial) Serial.println("Serial is not ok.");
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
}

void loop() {
  digitalWrite(3, HIGH);
  delay(2000);
  digitalWrite(3, LOW);
  digitalWrite(4, HIGH);
  delay(500);
  digitalWrite(4, LOW);
  delay(500);
  digitalWrite(4, HIGH);
  delay(500);
  digitalWrite(4, LOW);
  digitalWrite(5, HIGH);
  delay(2000);
  digitalWrite(5, LOW);
}