int LED1 = 2; 
int LED2 = 4;
int LED3 = 5;
int t1 = 250;
int t2 = 500;

void setup() {

  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
}

void blink_1()
{

  digitalWrite(LED1, HIGH );
  delay(t1);
  digitalWrite(LED2,HIGH);
  delay(t1);
  digitalWrite(LED3,HIGH);
  delay(t1);
  digitalWrite(LED1, LOW );
  delay(t1);
  digitalWrite(LED2,LOW);
  delay(t1);
  digitalWrite(LED3,LOW);
  delay(t1);


  digitalWrite(LED1, LOW);
  digitalWrite(LED2,LOW);
  digitalWrite(LED3,LOW);
  delay(t1);

}

void blink_2()
{

  digitalWrite(LED3, HIGH );
  delay(t1);
  digitalWrite(LED2,HIGH);
  delay(t1);
  digitalWrite(LED1,HIGH);
  delay(t1);
  digitalWrite(LED3, LOW );
  delay(t1);
  digitalWrite(LED2,LOW);
  delay(t1);
  digitalWrite(LED1,LOW);
  delay(t1);


  digitalWrite(LED1, LOW);
  digitalWrite(LED2,LOW);
  digitalWrite(LED3,LOW);
  delay(t1);
}

void blink_3()
{

  digitalWrite(LED1,HIGH );
  digitalWrite(LED2,LOW);
  digitalWrite(LED3,HIGH);
  delay(t2);
  digitalWrite(LED1, LOW );
  digitalWrite(LED2,HIGH);
  digitalWrite(LED3,LOW);
  delay(t2);

  digitalWrite(LED1, LOW);
  digitalWrite(LED2,LOW);
  digitalWrite(LED3,LOW);
  delay(t2);

}

void loop() 
{
  blink_1();
  blink_2();
  blink_3();
}