1,2

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

R. C. Read, The Enumeration of Mating-Type Graphs. Report CORR 89-38, Dept. Combinatorics and Optimization, Univ. Waterloo, Oct 1989.

Sequence in context: A156516 A067962 A134716 this_sequence A039748 A007764 A015195

Adjacent sequences: A006020 A006021 A006022 this_sequence A006024 A006025 A006026

nonn

Simon Plouffe (simon.plouffe(AT)gmail.com)