int i;
void setup()
{
for (i=2; i<=9; i++) 
pinMode(i, OUTPUT);
}
  void loop()
{
for (i=2; i<=9; i++)
{
  digitalWrite(i,1);
  digitalWrite(11-i,1);
  delay(200);
  digitalWrite(i,0);
  digitalWrite(11-i,0);
  }
}