int ledPinR = 23; 		// the number of the LED pin 
int ledPinG = 18; 
int ledPinY = 19;
int ledState1 = LOW; 	// ledState used to set the LED
int ledState2 = LOW; 
int ledState3 = LOW; 
long previousMillis1 = 0; 	// will store last time LED 
long previousMillis2 = 0;
long previousMillis3 = 0;
int interval1 = 1000;	// interval at which to blink (milliseconds) 
int interval2 = 500;
int interval3 = 2000;

void setup() 
{ 
pinMode(ledPinR, OUTPUT); 
pinMode(ledPinG, OUTPUT); 
pinMode(ledPinY, OUTPUT);
} 

void loop() 
{ 
long currentMillis = millis(); 
if ( currentMillis - previousMillis1 >= interval1) 
  { 
    previousMillis1 = currentMillis; // save the last time you blinked the LED 
  	if (ledState1 == LOW)
 	    { 
        ledState1 = HIGH;
 	    }
    else 
      { 
        ledState1 = LOW; 
      } 
  }

if ( currentMillis - previousMillis2 >= interval2) 
{ 
  previousMillis2 = currentMillis; // save the last time you blinked the LED 
 	if (ledState2 == LOW)
 	{ 
    ledState2 = HIGH;
 	}
  else 
  { 
    ledState2 = LOW; 
  } 
}

if ( currentMillis - previousMillis3 >= interval3) 
{ 
  previousMillis3 = currentMillis; // save the last time you blinked the LED 
 	if (ledState3 == LOW)
 	{ 
    ledState3 = HIGH;
 	}
  else 
  { 
    ledState3 = LOW; 
  } 
}
digitalWrite(ledPinR, ledState1); 
digitalWrite(ledPinG, ledState2); 
digitalWrite(ledPinY, ledState3);
}