int i;

void setup() {
	for (i=2;i<=9;i++) {
		pinMode(i,OUTPUT);
	}
}

void loop() {
 	i = 2;
 	while ((i <= 9)) {
 		digitalWrite(i, HIGH);
  	delay(150);
  	digitalWrite(i, LOW);
  	i++;
  }
	i--;
  while ((i >= 2)) {
  	digitalWrite(i, HIGH);
  	delay(150);
  	digitalWrite(i, LOW);
  	i--;
  }
}