1,3

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

R. W. Robinson, personal communication.

R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1979.

R. W. Robinson, Table of n, a(n) for n = 1..22

Sequence in context: A006198 A167588 A113573 this_sequence A075000 A077307 A112960

Adjacent sequences: A007127 A007128 A007129 this_sequence A007131 A007132 A007133

nonn

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