==== OEIS Primal ====

    * [[http://oeis.org/A137613|A137613]]
    * [[http://oeis.org/A221869|A221869]]
    * [[http://oeis.org/A167195|A167195]]
    * [[http://oeis.org/A167170|A167170]]
    * [[http://arxiv.org/abs/0910.4676]]