#define LED1 21
#define LED2 15
#define LED3 4
#define LED4 5

void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  pinMode(LED4, OUTPUT);
}

void loop() {
 digitalWrite(LED1, HIGH);
 delay(300);
 digitalWrite(LED1, LOW);
 delay(50);
 digitalWrite(LED2, HIGH);
 delay(20);
 digitalWrite(LED2, LOW);
 delay(100);
 digitalWrite(LED1, HIGH);
 delay(300);
 digitalWrite(LED1, LOW);
 delay(50);
 digitalWrite(LED3, HIGH);
 delay(50);
 digitalWrite(LED3, LOW);
 delay(20);
 digitalWrite(LED1, HIGH);
 delay(300);
 digitalWrite(LED1, LOW);
 delay(50);
 digitalWrite(LED4, HIGH);
 delay(300);
 digitalWrite(LED4, LOW);
 delay(50);
 digitalWrite(LED1, HIGH);
 delay(300);
 digitalWrite(LED1, LOW);
 delay(50);
 
}