uint8_t randomNumber()
{
  static uint8_t number = UINT8_MAX;
  const uint8_t old_number = number;

  while ( old_number == number )
  {
    number = random( 0, 9 );
  }

  return number;
}


void setup()
{
  Serial.begin( 115200 );
}


void loop()
{
  Serial.println( randomNumber() );
  delay( 250 );
}