const int ledPinRed = 3;
const int ledPinBlue = 2;
const int ledPinGreen = 1;

void setup() {
  pinMode(ledPinBlue, OUTPUT);
  pinMode(ledPinRed, OUTPUT);
  pinMode(ledPinGreen, OUTPUT);
}

void loop() {
  digitalWrite(ledPinBlue, HIGH);  // turn the LED off
  digitalWrite(ledPinRed, HIGH);
  digitalWrite(ledPinGreen, HIGH);
  delay(1000);
  digitalWrite(ledPinBlue, LOW);   // turn the Blue LED on
  delay(1000);
  digitalWrite(ledPinBlue, HIGH);  // turn the Blue LED off
  digitalWrite(ledPinRed, LOW);    // turn the Red LED on
  delay(1000);
  digitalWrite(ledPinRed, HIGH);   // turn the Red LED off
  digitalWrite(ledPinGreen, LOW);  // turn the Green LED on
  delay(1000);
}