1,3

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

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

W. T. Tutte, A census of Hamiltonian polygons, Canad. J. Math., 14 (1962), 402-417.

Cf. A000309, A000356, A004304.

Sequence in context: A027614 A121873 A107596 this_sequence A009053 A077054 A032332

Adjacent sequences: A000261 A000262 A000263 this_sequence A000265 A000266 A000267

nonn,nice

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

Better definition from Michael Albert, Oct 24 2008