int ledPins[]={2,3,4,5,6,7,8,9};
int pinCount=8;
int timer=200;
int thisPin ;


void setup() {
  // put your setup code here, to run once:
  for(int thisPin=0; thisPin<pinCount ;thisPin++){
    pinMode(ledPins[thisPin], OUTPUT);
  }
}

void loop() {
  // put your main code here, to run repeatedly:


  for( (thisPin) = 0; (thisPin) <= pinCount; thisPin++){
    
    delay(50);
    digitalWrite(ledPins[(2*thisPin)-1], HIGH);
    delay(timer);
     digitalWrite(ledPins[2*thisPin], HIGH);
    delay(timer);

    digitalWrite(ledPins[(2*thisPin)-1], LOW);
    delay(timer);
    
    digitalWrite(ledPins[2*thisPin], LOW);
   
   
  }
}