const int pins[] = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 }; 

void setup() 
{ 
  for (int i = 0; i < 10; i++) 
  { 
    pinMode(pins[i], OUTPUT); 
  } 
} 

int counter = 0; 

void loop() 
{ 
  for (int i = 0; i < 10; i++) 
  { 
    digitalWrite(pins[i], bitRead(counter, i) ? HIGH : LOW); 
  } 
  counter++; 
  delay(500); 
}