1,3

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

R. C. Read, Some Enumeration Problems in Graph Theory. Ph.D. Dissertation, Department of Mathematics, Univ. London, 1958.

R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976.

R. W. Robinson, Table of n, a(n) for n = 1..29

Sequence in context: A007100 A103157 A007099 this_sequence A002829 A145410 A005983

Adjacent sequences: A004106 A004107 A004108 this_sequence A004110 A004111 A004112

nonn,nice

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