1,3

I'm not sure how this differs from A000228.

J. V. Knop et al., On the total number of polyhexes, Match, No. 16 (1984), 119-134.

Cf. A018190, A038143-A038146.

Sequence in context: A018190 A000228 A108070 this_sequence A082271 A069505 A032403

Adjacent sequences: A038144 A038145 A038146 this_sequence A038148 A038149 A038150

nonn

N. J. A. Sloane (njas(AT)research.att.com).