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. A003223, A003225.
Sequence in context: A027851 A120765 A051812 * A156310 A142725 A175555
Adjacent sequences: A003221 A003222 A003223 * A003225 A003226 A003227
nonn,easy,more
N. J. A. Sloane (njas(AT)research.att.com).
