3,2
F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 171.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
E. M. Palmer and R. W. Robinson, Enumeration under two representations of the wreath product, Acta Math., 131 (1973), 123-143.
Cf. A003224, A003223.
Sequence in context: A184098 A067210 A018654 * A203104 A007663 A018695
Adjacent sequences: A003222 A003223 A003224 * A003226 A003227 A003228
nonn,easy,more
N. J. A. Sloane (njas(AT)research.att.com).
