0,5
Cheng-Sloane, Discrete Math. vol. 83 pp. 205-212 1990.
Cf. A014488.
Sequence in context: A060566 A031537 A031717 * A122707 A057327 A057328
Adjacent sequences: A030058 A030059 A030060 * A030062 A030063 A030064
nonn,fini,full
N. J. A. Sloane (njas(AT)research.att.com).