1,3

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

F. Harary and R. W. Robinson, Labeled bipartite blocks, Canad. J. Math., 31 (1979), 60-68.

Sequence in context: A138590 A069223 A129056 this_sequence A033511 A067156 A104785

Adjacent sequences: A005331 A005332 A005333 this_sequence A005335 A005336 A005337

nonn

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