int LedPins [] = {13,12,11,10,9,8,7,6};



void setup() 
{
  for (int i = 0; i < 8; i++)
  {
    pinMode(LedPins[i], OUTPUT);
  }
  randomSeed(millis());    //Initialize random number generator
}

void loop() 
{
  // Turn on by choice (select from array)
  digitalWrite(LedPins[0], HIGH);
  delay(200);
  digitalWrite(LedPins[0], LOW);
  delay(200);
  digitalWrite(LedPins[2], HIGH);
  delay(200);
  digitalWrite(LedPins[2], LOW);
  delay(200);
  digitalWrite(LedPins[4], HIGH);
  delay(200);
  digitalWrite(LedPins[4], LOW);
  delay(200);
  digitalWrite(LedPins[6], HIGH);
  delay(200);
  digitalWrite(LedPins[6], LOW);
  delay(200);

  // Turn on simple sequence
  for (int i = 0; i < 8; i++)
  {
    digitalWrite(LedPins[i], HIGH);
    delay(200);
    digitalWrite(LedPins[i], LOW);
    delay(200);
  }

  // Reverse
   for (int i = 7; i > -1; i--)
  {
    digitalWrite(LedPins[i], HIGH);
    delay(200);
    digitalWrite(LedPins[i], LOW);
    delay(200);
  }

  // random sequence
  for(int i = 0; i < 8; i++)
  {
    int randomIndex = random(0,8);
    digitalWrite(LedPins[randomIndex], HIGH);
    delay(200);
    digitalWrite(LedPins[randomIndex], LOW);
    delay(200);
  } 

  // Sequential on/off
  for(int i = 0; i < 8; i++)
  {
    digitalWrite(LedPins[i], HIGH);
    delay(200);
  }  
  for(int i = 7; i > -1; i--)
  {
    digitalWrite(LedPins[i], LOW);
    delay(200);
  } 
}