1,2

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

R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math., 31 (1986), 47-63.

Sequence in context: A151065 A151066 A151067 this_sequence A050385 A123768 A005750

Adjacent sequences: A007160 A007161 A007162 this_sequence A007164 A007165 A007166

nonn

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