void setup() {
   pinMode(3, OUTPUT);
   pinMode(4, OUTPUT);
}

void loop() {
  digitalWrite(3, HIGH);
  delay(5*1000);
  digitalWrite(3, LOW);
  delay(50); 
  digitalWrite(4, HIGH);
  delay(3*1000);
  digitalWrite(4, LOW);
  delay(50);
  digitalWrite(5, HIGH);
  delay(7*1000);
  digitalWrite(5, LOW);
  delay(50);
  digitalWrite(4, HIGH);
  delay(3*1000);
  digitalWrite(4, LOW);
  delay(50);
  digitalWrite(3, HIGH);
  delay(2*1000);
  digitalWrite(3, LOW);
  delay(50);
}