// Define necessary pins
const int ledPin = 26;
const int ledPin2 = 0;
const int ledPin3 = 1;

void setup() {
  // Initialize pins as outputs
  pinMode(ledPin, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(ledPin3, OUTPUT);
}

void loop() {
  for (int i = 0; i < 8; i++) {
    // Start sequence with all LEDs off
    digitalWrite(ledPin, LOW);
    digitalWrite(ledPin2, LOW);
    digitalWrite(ledPin3, LOW);
    Serial.println(i);

    // Convert int to binary and then string
    String b = String(i, BIN);

    // Turn on LED 001
    if (b.charAt(b.length() - 1) == '1') {
      digitalWrite(ledPin, HIGH);
    }
    // Turn on LED 010
    if (b.charAt(b.length() - 2) == '1') {
      digitalWrite(ledPin2, HIGH);
    }
    // Turn on LED 100
    if (b.charAt(b.length() - 3) == '1') {
      digitalWrite(ledPin3, HIGH);
    }
    delay(1000);
  }
}