Lindenmayer systems and primes
  We study the surprising discrepancy between the number of primes corresponding, respectively, to the two letters of an infinite word engendered by one of the simplest Lindenmayer systems. We formulate a conjecture concerning the rate of growth of this discrepancy, which seems to tend to e for every two sufficiently high consecutive even rank iterates of the Lindenmayer system. 
Andrei Vieru