int a[6]={5,18,19,21,22,23};
void setup() {
 for(int i=0; i<=5;i++){
   pinMode(a[i], OUTPUT);
  }

}

void loop() {
  for(int i=0; i<=5;i++){
   digitalWrite(a[i], HIGH);
   delay(500);
   digitalWrite(a[i], LOW);
   delay(500);
   digitalWrite(a[i], HIGH);
   delay(500);
   digitalWrite(a[i], LOW);
   delay(500);
   digitalWrite(a[i], HIGH);
   delay(500);
   digitalWrite(a[i], LOW);
   delay(500);
  }
  
 
}