3,2

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

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 171.

E. M. Palmer and R. W. Robinson, Enumeration under two representations of the wreath product, Acta Math., 131 (1973), 123-143.

Cf. A003223, A003225.

Adjacent sequences: A003221 A003222 A003223 this_sequence A003225 A003226 A003227

Sequence in context: A027851 A120765 A051812 this_sequence A142725 A070387 A123748

nonn,easy,more

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