2,1
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Sequence in context: A001567 A178723 A006970 * A007011 A064907 A043685
Adjacent sequences: A007321 A007322 A007323 * A007325 A007326 A007327
nonn
N. J. A. Sloane (njas(AT)research.att.com), bach(AT)cs.wisc.edu (Eric Bach)