#define LED1 18  // D18
#define LED2 19  // D19
#define LED3 21  // D21

void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
}

void loop() {
  // Sequence 1: One by one
  digitalWrite(LED1, HIGH);
  delay(500);
  digitalWrite(LED1, LOW);
  delay(500);
  
  digitalWrite(LED2, HIGH);
  delay(500);
  digitalWrite(LED2, LOW);
  delay(500);
  
  digitalWrite(LED3, HIGH);
  delay(500);
  digitalWrite(LED3, LOW);
  delay(500);

  delay(1000);  // Wait for 1 second before starting the next sequence
  
  // Sequence 2: All LEDs blink simultaneously
  digitalWrite(LED1, HIGH);
  digitalWrite(LED2, HIGH);
  digitalWrite(LED3, HIGH);
  delay(500);
  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
  digitalWrite(LED3, LOW);
  delay(500);

  delay(1000);  // Wait for 1 second before starting the next sequence

  // Sequence 3: Alternating LEDs
  digitalWrite(LED1, HIGH);
  digitalWrite(LED3, HIGH);
  delay(500);
  digitalWrite(LED1, LOW);
  digitalWrite(LED3, LOW);

  digitalWrite(LED2, HIGH);
  delay(500);
  digitalWrite(LED2, LOW);
  
  delay(1000);  // Wait for 1 second before repeating the sequences
}