1,2
T. J. McLarnan, The numbers of polytypes ..., Zeits. Krist. 155, 269-291 (1981).
Sequence in context: A018679 A018741 A161704 * A060172 A193196 A003243
Adjacent sequences: A011959 A011960 A011961 * A011963 A011964 A011965
nonn,easy
N. J. A. Sloane (njas(AT)research.att.com).