Hypnotoad

// All glory to the Hypnotoad

const int LED_NUM = 3;
const int LEDa[LED_NUM] = {13, 12, 11};
const int LEDb[LED_NUM] = {7,  6,  5 };

void setup() {
  for (i=0; i<LED_NUM; i++)
  {
    pinMode(LEDa[i], OUTPUT);   // set output
    digitalWrite(LEDa[i], LOW); // LED off
    pinMode(LEDb[i], OUTPUT);   // set output
    digitalWrite(LEDb[i], LOW); // LED off
  }
}

void loop()
{
  const int MS = 90;
  static int i = 0;

  if (i == LED_NUM) i = 0;
  digitalWrite(LEDa[i], HIGH);   // LED on
  digitalWrite(LEDb[i], HIGH);   // LED on
  delay(MS);                     // wait
  digitalWrite(LEDa[i], LOW);    // LED off
  digitalWrite(LEDb[i], LOW);    // LED off
  ++i;
}