1,5

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 18, col. 4 of Table 1.5.1 (divided by 64).

R. C. Read, The number of k-colored graphs on labeled nodes, Canad. J. Math., 12 (1960), 410-414.

R. C. Read, personal communication.

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

Cf. A000683. A diagonal of A058843.

Sequence in context: A017743 A004390 A076004 this_sequence A116252 A159734 A091754

Adjacent sequences: A006199 A006200 A006201 this_sequence A006203 A006204 A006205

nonn,easy

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