// ORIGINALSCRIPT: https://forum.arduino.cc/index.php?topic=410213.0

#define ELEMENTS(x)   (sizeof(x) / sizeof(x[0]))
int one[] = {2, 3, 4, 5, 6, 7, 8, 9}; // Let the computer count how many elements you need

void setup() {

  for (int i = 0; i < 20; i++) {
    pinMode(i, OUTPUT);
  }

}

void loop() {

  yourLED(one);

}

// -------------------------------------------------------------

void yourLED(int myArray[]) {
  int i;

  for (i = 0; i < ELEMENTS(one); i++) {

    digitalWrite(myArray[i], HIGH);
    delay(500);               // wait for a pause
    digitalWrite(myArray[i], LOW);
    delay(500);               // wait for a pause

  }

}