// Define LED Pins
#define LED1 18
#define LED2 19
#define LED3 21

void setup() {
  // Set LED pins as OUTPUT
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
}

void loop() {
  // Simple Sequence
  digitalWrite(LED1, HIGH);
  delay(500);
  digitalWrite(LED1, LOW);
  
  digitalWrite(LED2, HIGH);
  delay(500);
  digitalWrite(LED2, LOW);
  
  digitalWrite(LED3, HIGH);
  delay(500);
  digitalWrite(LED3, LOW);

  // Blink All
  digitalWrite(LED1, HIGH);
  digitalWrite(LED2, HIGH);
  digitalWrite(LED3, HIGH);
  delay(500);
  
  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
  digitalWrite(LED3, LOW);
  delay(500);

  // Knight Rider (Back and Forth)
  digitalWrite(LED1, HIGH);
  delay(300);
  digitalWrite(LED1, LOW);
  
  digitalWrite(LED2, HIGH);
  delay(300);
  digitalWrite(LED2, LOW);
  
  digitalWrite(LED3, HIGH);
  delay(300);
  digitalWrite(LED3, LOW);
  
  digitalWrite(LED2, HIGH);
  delay(300);
  digitalWrite(LED2, LOW);
}