int delayTime = 1000; // time of delay in ms

void setup(){
  // setting up pins 9-13 as output
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
}

void loop(){
  // iteration from pin 13 to pin 9
  digitalWrite(13, HIGH);
  delay(delayTime); 
  digitalWrite(13, LOW);
  digitalWrite(12, HIGH);
  delay(delayTime); 
  digitalWrite(12, LOW);
  digitalWrite(11, HIGH);
  delay(delayTime); 
  digitalWrite(11, LOW);
  digitalWrite(10, HIGH);
  delay(delayTime); 
  digitalWrite(10, LOW);
  digitalWrite(9, HIGH);
  delay(delayTime); 
  digitalWrite(9, LOW);
}