//christmas lights, for example all on, all off, 
// then  bulbs 1,3,5 on and 2., 4 off then vice versa.

void setup() {
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
} 

void loop() {
  // all bulbs on
  digitalWrite(13, HIGH); // LED ON
  digitalWrite(12, HIGH); // LED ON
  digitalWrite(11, HIGH); // LED ON
  digitalWrite(10, HIGH); // LED ON
  digitalWrite(9, HIGH); // LED ON
  delay(1000);
  
  // all bulbs off
  digitalWrite(13, LOW); // LED OFF
  digitalWrite(12, LOW); // LED OFF
  digitalWrite(11, LOW); // LED OFF
  digitalWrite(10, LOW); // LED OFF
  digitalWrite(9, LOW); // LED OFF
  delay(1000);

  // bulbs 1,3 and 5 on
  digitalWrite(13, HIGH); // LED ON
  digitalWrite(12, LOW); // LED OFF
  digitalWrite(11, HIGH); // LED ON
  digitalWrite(10, LOW); // LED OFF
  digitalWrite(9, HIGH); // LED ON
  delay(1000);

  // bulbs 2 and 4 on
  digitalWrite(13, LOW); // LED OFF
  digitalWrite(12, HIGH); // LED ON
  digitalWrite(11, LOW); // LED OFF
  digitalWrite(10, HIGH); // LED ON
  digitalWrite(9, LOW); // LED OFF
  delay(1000);
  
}