2,1
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
P. E. Wood, Jr., Switching Theory, McGraw-Hill, 1968, see p. 263.
Cf. A006845.
Sequence in context: A145618 A169900 A140355 * A028424 A175270 A037311
Adjacent sequences: A007038 A007039 A007040 * A007042 A007043 A007044
nonn
N. J. A. Sloane (njas(AT)research.att.com).